Joy2Key is a program that i use to map the buttons. Works really well and it is also possible to map multiple game controllers to diverse function. (I have an additional gamepad attached to my wheel for the f12 stuff.) This way I also use button clutch now, although i am not sure, if this makes me any faster...
I once had a link to the original download destination, somehow it doesn't seem to work anymore, but you can download it on our team website (drt.net.tc) in downloads, tool, page 2, jtk374en.zip
Have fun