var myInt = 1;

... myIntの値が変更された場合 ...

function myTraceFunction():void {
  trace(myInt);
}

this.myInt.addEventListener(Event.xxxx, myTraceFunction);

function myTraceFunction(e:Event):void {
  trace(e.currentTarget.xxx);
  //出力: 2
}

// テスト用スクリプト
var obj:Test = new Test();
obj.myInt = 1;

// ActionScript 3.0クラス定義ファイル: Test.as
package {
	public class Test {
		private var _myInt:int = 0;
		public function Test() {}
		public function get myInt():int {
			return _myInt;
		}
		public function set myInt(i:int):void {
			_myInt = i;
			myTraceFunction();
		}
		private function myTraceFunction():void {
			trace(myInt);
		}
	}
}