set duration to tween in loop

how can i set duration to a tween to which i set loop using yoyo?

import fl.transitions.Tween;

import fl.transitions.easing.*;

import fl.transitions.TweenEvent;

var myTween = new Tween(sounds_click, "x", Elastic.easeInOut, 325,335, 0.1, true);

myTween.addEventListener(TweenEvent.MOTION_FINISH, onFinish);

function onFinish(e:TweenEvent):void {

myTween.yoyo();

}