I probably shouldn't've answered since I won't be much help...
You'll need go into the cfg folder, edit the cfg file for that game/s with wordpad.exe.
that is all written in ...xml(?). As for what to do here...
But yeah. It can be done. I have a couple driving/racing games where I'll use a certain button to pause that isn't the same button on my standard controller that I use with other games.