How do I do this?

Can someone tell me how I do the following with a picture:

http://www.babyvoxi.com

It’s a really nice effect.
I’ve tried using mx.transitions.Tween actions.
I figured that the picture needed to go X times the mouse position.

I’ve got some code working where, if the mouse goes up 1cm, the picture goes up 2cm, for example.
But… what I can’t figure out is how to control the movement, so that when the mouse goes down, the picture goes down, similarly for up.

In my code, the picture just follows the mouse with a magnified movement because I’m multiplying by a number.

I’m scratching my head over this one.
Any help would be appreciated.

Thanks.

OM