[nauroman]

Сделал, так :

<?xml version="1.0" encoding="utf-8"?>
<s:Label xmlns:fx="http://ns.adobe.com/mxml/2009" 
		 xmlns:s="library://ns.adobe.com/flex/spark" 
		 xmlns:mx="library://ns.adobe.com/flex/mx"
		 addedToStage="onAddedToStage()"
		 backgroundColor="#FF0000">
	<fx:Declarations>
		<!-- Place non-visual elements (e.g., services, value objects) here -->
	</fx:Declarations>
 
	<fx:Script >
		<![CDATA[
 
			private var _width:Number;
			private var _height:Number;
 
			protected function onAddedToStage():void
			{				
				width = _width;
				height = _height;
			}
 
			override public function set width(value:Number):void
			{
				trace("set width : " + value);
 
				if (isNaN(value)) return;
 
				_width = value;
 
				var boundsWidth:Number = getBounds(this).width;
 
				if (!boundsWidth)
				{
					return;
				}
 
				scaleX = _width / boundsWidth;
			}
 
			override public function set height(value:Number):void
			{
				trace("set height : " + value);
 
				if (isNaN(value)) return;
 
				_height = value;
 
				var boundsHeight:Number = getBounds(this).height;
 
				if (!boundsHeight)
				{
					return;
				}
 
				scaleY = _height / boundsHeight;
			}
 
		]]>
	</fx:Script>
 
</s:Label>