import fl.transitions.Tween;
import fl.transitions.easing.*;
import fl.transitions.TweenEvent;
var at:Array = new Array();
at.push(new Tween(stageitem, 'x',Strong.easeIn,0, 500,2,true ));
//Here
// Instance Name of Movie Clip is (stageitem)
// 0 = Start Frame
// 500 = End Frame
// 2 = Time Duration
at[0].addEventListener(TweenEvent.MOTION_FINISH, done);
function done(e:Event)
{
at[0].yoyo();
}
View Demo