A few months ago I had released an easing tween class  that I wrote in AS2 based on the easing formula posts.  The basic principle is to get a clip to move, scale or rotate from point A to B with different movement equations. this is an alternative class similar to the fuse kit, the Robert Penner equations, the Zeh Fernando MC tween, the Zigo/Laco or the tween classes found in Flash.  Here is the principle

	import com.reflektions.tween.*;	

	var tween:Tween = new Tween();
	var tobj:Object = {mc:mc,x:x,dx:dx}; 	//x init and dx final position
	tween.initTween(tobj);
	

I rewrote the class in AS3 and you can download it here.  I also added custom event dispatchers that dispatch events when the clip is animating and when tween completed.  The  movieclip reference and time (0 to 1) are also passed through the custom event.

	// Add Listener to tween events
	tween.addEventListener(TweenEventDispatcher.TWEEN_PROGRESS, progressListener);
	tween.addEventListener(TweenEventDispatcher.TWEEN_COMPLETE, completeListener); 

n.b: as far as passing properties go you can pass (x:,dx:) for x tweening, (y:,dy:) for y tweening, (r:,dr:) for rotation, (a:,da:) for transparency and (xscale:,dxscale:) and (y:,dyscale:) for scaling on both axis.  Enjoy, here is an examples that tweens 5 different clips with different equations at different speeds.