XML Menu expand up

I need to get this to expand UP.

/* LOAD XML NAVIGATION */
////////////////////////////////////////////////////////
// ************ Configuration *********************** //
// general 
// main buttons
var mainX = -759.3;
var mainY = 10;
var mainBtnSpacing:Number = 1;
var mainBg:Number = 0xEBEAEA;
var mainText:Number = 0xD5D5D5;
var mainActiveText:Number = 0x499FD8;
// sub buttons 
var slideInSpeed:Number = 0.5;
var slideOutSpeed:Number = 0.5;
var subMenuX:Number = 161;
var subBg:Number = 0x000000;
var subActiveBg:Number = 0x1A1A1A;
var subBtnSpacing:Number = 34;
// ************ End of Configuration *************** //
////////////////////////////////////////////////////////
// import needed classes 
import mx.transitions.Tween;
import mx.transitions.easing.*;
// set scope to this to avoid path issues 
var scope:MovieClip = this;
scope.createEmptyMovieClip("mainMenu",2);

// postion menu
mainMenu._x = mainX;
mainMenu._y = mainY;

// set the mask to hide menu when it goes past top level buttons
//var mask:MovieClip = mainMenu.attachMovie("mask", "mask", 100);
mask._width = 50; //Stage.width;
mask._height = 50; //Stage.height;
mask._y = Stage.height-50;
//mask._alpha = 0;
//mainMenu.setMask(mask);

// used in createSubMenu function to choose which sub menu to close
var switcher:Boolean = true;
// Load XML
var menuXml:XML = new XML();
menuXml.ignoreWhite = true;
menuXml.onLoad = buildMenu;
menuXml.load("content/xml/menu.xml");
//menuXml.load("http://192.168.134.90/JoomlaEcom/read/index.php?action=top_level_cats");

// Build Menu
function buildMenu(success:Boolean):Void {
    if (success) {
        button = this.firstChild.childNodes;
        var i:Number;
        for (i=0; i<button.length; i++) {
            var mainBtn:MovieClip = mainMenu.attachMovie("mainBtn", "mainBtn"+i, i+500);
            mainBtn.btnName.text = button*.attributes.NAME;
            mainBtn.link = button*.attributes.LINK;
            mainBtn.subMenu = button*.childNodes.length;
            // positon top menu buttons
            mainBtn._x += mainMenu["mainBtn"+(i-1)]._x+mainMenu["mainBtn"+(i-1)]._width+mainBtnSpacing;
            // hide overMc
            mainBtn.overMc._alpha = 0;
            // if menu has sub menus
            if (mainBtn.subMenu) {
                mainBtn.subbutton = button*.childNodes;
                mainBtn.createSubMenu = function():Void  {
                    // choose which menu to close
                    var subMenu:MovieClip = mainMenu.createEmptyMovieClip("subMenu", i);
                    // set current sub menu
                    currSub = subMenu;
                    var j:Number;
                    for (j=0; j<this.subMenu; j++) {
                        // create subBtns 
                        var subBtn:MovieClip = subMenu.attachMovie("subBtn", "subBtn"+j, j+9000);
                        // slide in sub menu
                        slide(subBtn,currSub._y,subBtn._height-subBtnSpacing*(j),slideInSpeed+j*0.4,"_y",Elastic.easeOut);
                        //slide(subBtn,0,subBtn._height+subBtnSpacing*(j),slideInSpeed+j*0.4,"_y",Elastic.easeOut);
                        subBtn.btnName.text = this.subbutton[j].attributes.NAME;
                        subBtn.link = this.subbutton[j].attributes.LINK;
                        // set sub bg color
                        var subBgColor = new Color(subBtn.bg);
                        subBgColor.setRGB(subBg);
                        // position subBtns
                        subBtn._x = activeMain._x;
                        // sub button events 
                        subBtn.onRelease = function():Void  {
                            /* Links are set in the xml (the FILE LINK attribute) and are accessible by 
                            using "this.link" so you might want to do something like: 
                            scope.createEmptyMovieClip("placeholder", 2000);
                            loadMovie(this.link, placeholder);
                            if you want to open a http:// link try:
                            getURL(this.link, "_blank");
                            */
                            trace(this.link);
                        };
                        subBtn.onRollOver = function():Void  {
                            var subActiveColor = new Color(this.bg);
                            subActiveColor.setRGB(subActiveBg);
                        };
                        subBtn.onRollOut = function() {
                            var subNormalColor = new Color(this.bg);
                            subNormalColor.setRGB(subBg);
                        };
                    }
                    /* hit zone is used to create an area that if rolled over closes the menu.
                    we use the mask mc again to save file size
                    */
                    var hitZone:MovieClip = scope.attachMovie("mask", "hitZone", 1);
                    hitZone._x = mainX+currButton._x-50;
                    hitZone._y = currButton._y-999;
                    hitZone._width = subMenu._width+100;
                    hitZone._height = subMenu._height+subBtnSpacing+mainY+1000;
                    // comment this line out if you want to see where it is positoned
                    hitZone._alpha = 0;
                    hitZone.useHandCursor = false;
                    hitZone.onRollOver = function() {
                        slider.stop();
                        closeMenu();
                    };
                };
                mainBtn.onRollOver = function():Void  {
                    slider.stop();
                    currButton.overMc._alpha = 0;
                    this.overMc._alpha = 100;
                    if (activeMain != this) {
                        activeMain = this;
                        activeStates(this.btnName);
                        // build subs 
                        currButton = this;
                        this.createSubMenu();
                        stopQuick(hitZone);
                    }
                };
                //  events for buttons without subMenus
            } else {
                mainBtn.onRollOver = function():Void  {
                    currButton.overMc._alpha = 0;
                    this.overMc._alpha = 100;
                    if (activeMain != this) {
                        activeMain = this;
                        activeStates(this.btnName);
                        closeMenu();
                        currButton = this;
                    }
                };
                mainBtn.onRollOut = function():Void  {
                    this.overMc._alpha = 0;
                    activeStates(null,null);
                    activeMain = null;
                    currButton = null;
                };
                mainBtn.onRelease = function():Void  {
                    if (activeMain != this) {
                        /* Links are set in the xml (the button LINK attribute) and are accessible by 
                        using "this.link" so you might want to do something like: 
                        scope.createEmptyMovieClip("placeholder", 2000);
                        loadMovie(this.link, placeholder);
                        if you want to open a http:// link try:
                        getURL(this.link, "_blank");
                        */
                        trace(this.link);
                    }
                };
            }
        }
    } else {
        trace("XML Failed to Load");
    }
}
// timer to keep sub open
function stopQuick(button) {
    time = getTimer();
    scope.onEnterFrame = function() {
        time2 = getTimer();
        if (Number(time2-time)>2000) {
            button.enabled = true;
            delete scope.onEnterFrame;
        } else {
            button.enabled = false;
        }
    };
}
// close menu
function closeMenu():Void {
    currButton.overMc._alpha = 0;
    slide(currSub,currSub._y,-currSub._height,slideOutSpeed,"_y",Strong.easeOut);
    //slide(currSub,currSub._y,currSub._height,slideOutSpeed,"_y",Elastic.easeOut);
    activeStates(null,null);
    activeMain = null;
    currButton = null;
}
// set/remove active states
function activeStates(txt):Void {
    // set active state 
    txt.textColor = mainActiveText;
    // remove active state from former
    currButton.btnName.textColor = mainText;
}
// slide tween
function slide(who:MovieClip, startvalue:Number, endvalue:Number, y_speed:Number, prop:String, ease) {
    slider = new Tween(who, prop, ease, startvalue, endvalue, y_speed, true);
}

// ------------------------------------------------------- //

<?xml version="1.0" encoding="UTF-8"?>
<MENU>
    <BUTTON NAME="About Us">
        <SUB NAME="Submenu Link 1" LINK="sub1.swf" />
        <SUB NAME="Submenu Link 2" LINK="sub2.swf" />
        <SUB NAME="Submenu Link 3" LINK="sub3.swf" />
        <SUB NAME="Submenu Link 4" LINK="sub4.swf" />
    </BUTTON>
    <BUTTON NAME="News" LINK="news.swf">
        <SUB NAME="Submenu Link 1" LINK="sub1.swf" />
        <SUB NAME="Submenu Link 2" LINK="sub2.swf" />
        <SUB NAME="Submenu Link 3" LINK="sub3.swf" />
    </BUTTON>
    <BUTTON NAME="Services">
        <SUB NAME="Submenu Link 1" LINK="sub1.swf" />
        <SUB NAME="Submenu Link 2" LINK="sub2.swf" />
        <SUB NAME="Submenu Link 3" LINK="sub3.swf" />
        <SUB NAME="Submenu Link 4" LINK="sub4.swf" />
        <SUB NAME="Submenu Link 5" LINK="sub5.swf" />
    </BUTTON>
    <BUTTON NAME="Contact" LINK="contact.swf"/>
</MENU>