var myTween:Tween = new Tween(this, "scaleX", Back.easeIn, 1.2, 0, 10);
var myTween2:Tween = new Tween(this, "scaleY", Back.easeIn, 1.2, 0, 10);
var myTween3:Tween = new Tween(this, "alpha", None.easeIn, 1, 0, 10);

import fl.transitions.Tween;
import fl.transitions.TweenEvent;
import fl.motion.easing.Back;
import fl.transitions.easing.None;

// Populate an array with the tweens
var tweens:Array = [];
tweens.push(new Tween(this, "scaleX", Back.easeIn, 1.2, 0, 10));
tweens.push(new Tween(this, "scaleY", Back.easeIn, 1.2, 0, 10));
tweens.push(new Tween(this, "alpha", None.easeIn, 1, 0, 10));

// Finished tweens count
var finishedCount:int = 0;

// Loop through all the tweens and add a handler for the motion finished event
for (var i:int = 0; i < tweens.length; i ++)
{
    // Each of the tweens motion finished event can be assigned to the same handler
    Tween(tweens[i]).addEventListener(TweenEvent.MOTION_FINISH, motionFinishedHandler);
}

function motionFinishedHandler(e:TweenEvent):void
{
    // Good practice to remove the event listener when it is no longer needed
    e.target.removeEventListener(TweenEvent.MOTION_FINISH, motionFinishedHandler);

    // Increment the count and test whether it equals the number of tweens
    if (++ finishedCount == tweens.length)
        trace("Finished");
}