[silin]

например так:

mc.onPress=function(){
	var x=this._xmouse();
	var dx=3;
	this.onEnterFrame=function(){
		this._x+=this._xmouse-x+dx;
		x=this._xmouse;
	}
}
mc.onRelease=mc.onReleaseOutside=function(){
	delete this.onEnterFrame;
}