I have a tendency to make things more complex than they need to be. :-P

Okay, the steps are:

1. Take your Freak and your mattress. Pose your Freak appropriately so that he's pressing down on the mattress.
2. Create a magnet for the mattress and position it underneath Freak's hand, in the spot where you want to deform the mattress.
3. Place the magnet base on the surface of the mattress and place the magnet itself slightly below the surface of the mattress.
4. Scale the magnet and it's zone until it makes the right sized depression for Freak's fist.
5. Tweak the position of the different elements of the magnet to get the effect you want.

That should be it. I apologize for muddying the waters there with the more complex process. I had an animation method in mind that didn't require external scripts.

The above is just an example animation of the process I attempted to describe. That is, with a magnet created for the mattress and its magzone parented to the Freak's hand. But it seems that the deformer script does the job, probably with greater flexibility. I guess you can always fine tune things with magnets later on if need be.

nukem