Center scroller that moves slowly at first

1

So I have a horizontal scrollbar for a gallery of photos, and the cleint wants the dragger to start in the center of the track, rather than at the left hand side, and also wants it to be moving slowly automatically when it loads. Can anyone help me with that code?

I’m using this for my scrollbar. And here’s the link- http://www.evanimal.com/kidd
Go to the collection section in the main menu.

scrolling = function () {
var scrollHeight:Number = scrollTrack._height;
var contentHeight:Number = contentMain._height;
var scrollFaceHeight:Number = scrollFace._height;
var maskHeight:Number = maskedView._height;
var initPosition:Number = scrollFace._y=scrollTrack._y;
var initContentPos:Number = contentMain._y;
var finalContentPos:Number = maskHeight-contentHeight+initContentPos;
var left:Number = scrollTrack._x;
var top:Number = scrollTrack._y;
var right:Number = scrollTrack._x;
var bottom:Number = scrollTrack._height-scrollFaceHeight+scrollTrack._y;
var dy:Number = 0;
var speed:Number = 10;
var moveVal:Number = (contentHeight-maskHeight)/(scrollHeight-scrollFaceHeight);

scrollFace.onPress = function() {
    var currPos:Number = this._y;
    startDrag(this, false, left, top, right, bottom);
    this.onMouseMove = function() {
        dy = Math.abs(initPosition-this._y);
        contentMain._y = Math.round(dy*-1*moveVal+initContentPos);
    };
};
scrollFace.onMouseUp = function() {
    stopDrag();
    delete this.onMouseMove;
};
btnUp.onPress = function() {
    this.onEnterFrame = function() {
        if (contentMain._y+speed<maskedView._y) {
            if (scrollFace._y<=top) {
                scrollFace._y = top;
            } else {
                scrollFace._y -= speed/moveVal;
            }
            contentMain._y += speed;
        } else {
            scrollFace._y = top;
            contentMain._y = maskedView._y;
            delete this.onEnterFrame;
        }
    };
};
btnUp.onDragOut = function() {
    delete this.onEnterFrame;
};
btnUp.onRelease = function() {
    delete this.onEnterFrame;
};
btnDown.onPress = function() {
    this.onEnterFrame = function() {
        if (contentMain._y-speed>finalContentPos) {
            if (scrollFace._y>=bottom) {
                scrollFace._y = bottom;
            } else {
                scrollFace._y += speed/moveVal;
            }
            contentMain._y -= speed;
        } else {
            scrollFace._y = bottom;
            contentMain._y = finalContentPos;
            delete this.onEnterFrame;
        }
    };
};
btnDown.onRelease = function() {
    delete this.onEnterFrame;
};
btnDown.onDragOut = function() {
    delete this.onEnterFrame;
};

if (contentHeight<maskHeight) {
    scrollFace._visible = false;
    btnUp.enabled = false;
    btnDown.enabled = false;
} else {
    scrollFace._visible = true;
    btnUp.enabled = true;
    btnDown.enabled = true;
}

};
scrolling();