L1hm: just go into your control settings but change the key.. but nope, not even available.. is this even possible to do?
An alternative, albeit somewhat time consuming (maybe 30minutes) is to simply use an Xbox or Ps3 controller via Xpadder. You can re map the controller to emulate any keyboard strike or mouse click you want. If using a Ps3 or other non Xbox controller you'll need additional software which actually registers your controller as an Xbox (to your system).
I use Xpadder to play FPS when I don't care about competing and just want to drink a beer and blow some $hit up from my couch instead of sitting at a desk.