[zxcv]

		var button_up:Loader = new Loader();
		var button_down:Loader = new Loader();
		var btn:SimpleButton;
 
		public function Main()
		{
			button_up.contentLoaderInfo.addEventListener(Event.COMPLETE, compUp);
			button_up.load(new URLRequest("C:\\images\\button_up.png"));
			button_down.contentLoaderInfo.addEventListener(Event.COMPLETE, compDown);
			button_down.load(new URLRequest("C:\\images\\button_down.png"));
 
 
			var bmp:Bitmap = new Bitmap();
			btn = new SimpleButton(bmp,bmp,bmp);
			addChild(btn);
		}
 
 
		function compUp(event:Event)
		{
			trace("!!");
			btn.upState = button_up.content;
		}
 
 
		function compDown(event:Event)
		{
			trace("@@");
			btn.downState = button_down.content;
		}

вроде так