Pause mx.transition Tween?

programming flash
1

I need to pause this tween after it reaches 100% _alpha. Any recommendations?

function fadeImage() {
        myFade = new mx.transitions.Tween(box, "_alpha", mx.transitions.easing.Strong.easeOut, 0, 100, 1, true);
		myFade.onMotionFinished = function() {
			this.yoyo();
			}
		}

Thanks!