[murz]

нет у твинера таких праметров, только математикой

s = new Sprite();
var g:Graphics = s.graphics;
g.beginFill(0);
g.drawRect(0, 0, 100, 200);
g.endFill();
addChild(s);
var scale:Number = 0.2;
trace("centr pre scale:",s.x + (s.width >>1), s.y + (s.height>>1));
var p:Point = new Point(s.x + (s.width >> 1) - ((s.width * scale) >> 1), s.y + (s.height >> 1) -((s.height*scale) >> 1));
//trace(p);
Tweener.addTween(s, { scaleX:scale, scaleY:scale, x:p.x, y:p.y, delay: 2, time:0.5, onComplete: tweenCompleteHandler} );
 
function tweenCompleteHandler():void {
trace("centr after scale:",s.x + (s.width >>1), s.y + (s.height>>1));
}