PS3 Trackball

I have this idea to attach a small trackball to the right hand analogue stick on a PS3 controller. I'm thinking of just soldering the outputs on the trackball straight over the top of the current wires for the stick. Will this work or am I being a little naive?

Heres the trackball.
**broken link removed**


Heres where I plan to solder onto.
**broken link removed**

Do you guys have any idea as to what I should be wiring to and from. Dont laugh please, I'm desperate to get something working and am willing to give anything a go.

Kind Regards

Mike

Trackballs are relative positioning devices, joysticks are absolute so there's not going to be a simple solder on sollution to this idea. You'd need a relativly sophisticated sollution, such as a micro controller connected to the trackball with a rolling reset or some other method of turning the track balls relative position into an absolute one and a DAC to interface to the controller in place of the POT (joystick) to give the controller the translated position.

Rats.

How would I go about writing something like this? Which program/language is best?

Regards

Mike