[mre]

...
var i:int;
var ar:Array = new Array();
var mc:MovieClip;
for (i = 0; i < 10; i++)
{
    mc = this['menu' + i];
    mc.addEventListener(MouseEvent.ROLL_OVER, overHandler);
    ar.push(mc);
}
...
private function overHandler(event:MouseEvent):void
{
    var mc:MovieClip = event.target as MovieClip;
    mc.scaleX = 2;
}

arr.addEventListener

Ужасно.