Scroll bar help

Does anybody know how to put up and down arrows on this scroll bar?

function scrollBar (bar:MovieClip,mask:MovieClip,clip:MovieClip) {

clip.yInit=clip._y;
bar.slider._y=0;
bar.slider[“owner”]=this;
clip.yInit=clip._y;
bar._height=mask._height;

bar.slider.onPress=function () {
this.startDrag(false,0,0,0,bar.bg._height-this._height);
}

bar.slider.onMouseUp=function () {this.stopDrag();}

bar.bg.onPress=function(){
var yPos=bar._ymouse;
if (yPos>bar.bg._height-bar.slider._height) {yPos=bar.bg._height-bar.slider._height;}
bar.slider._y=yPos;
}

clip.onEnterFrame=function() {
if (this._height>mask._height) {
bar._visible=true;
var yLast:Number=(bar.slider._y*(this._height-mask._height))/(bar.bg._height-bar.slider._height);
this._y=this._y+((this.yInit-yLast)-this._y)/10;
} else {
bar._visible=false;
bar.slider._y=0;
this._y=this.yInit;
}
}