It's possible to combine multiple joysticks together into a single controller, but it's not the easiest thing to do. If you end up needing that route, you will need PPJoy and possibly GlovePIE.
Before you go to far, make sure you read BadMouth's thread on driving cabs and understand what kind of controls you have. I think you will have a 270° force feedback wheel in an OUt Run cabinet. I'm not sure how the pedals or shifter are set up, but that will also make a difference in knowing what will work. In any case, that wheel will be really nice for PC driving games! Be aware that you cannot play 360° games (Offroad, Sprint games, etc), though.
Good luck!