Ok, I was going to post my theory on my site when it's up, but here goes:
The Neo has a very simple electronic control setup. It has 1 pin on the controller port for every button (Up, Down, A, B, Start, etc). And one common wire for the voltage level (which in the Neo's case is +5V). So what has to be done is 3 steps (I think):
1.) Buy a 15 pin connnector with a wire attatched to it (it's the same pin size as a MIDI/Gameport on PC's, NOT THE 15 PIN MONITOR CABLE), open the sucker up and find out which wire go to what pin.
2.) Go to
www.gamesx.com and find out the controller pinout of the Neo. Write it down cause you are going to need it.
3.) Open up the controller of your choice, and remove the wire connections to the circuit board.
4.) (This is where I haven't tried yet, so it's theory, I'm going to test soon!)
Find the where you can connect the common wire (+5V) to the top of every button switch you will need on the controller.
5.) Then connect the corresponding wire from the Neo pinout to the other end of the switch for the button of your choice.
6.) Close up the controller and hope to god that this dumb guy on the Net isn't out of his mind.
Please I haven't tried this yet, but I will as soon as I get a car and the 15 pin connectors I need. If you do try this, do not hold me responsible for what happens to your controller and possibly your Neo! This is all theory and I haven't gotten to test it out yet. If it does work, I will open my site early and put up the tutorial for it with pics.
Peace
JHendrix