Maybe Carbuttons @ www.madhacker.org I believe might work.
CDRSkull had an app for using a usb analog gamepad and hardwiring to your switchs.
Alright, so heres the deal. I am working on a 2003 Audi A6 and replacing the factory 6CD changer and am changing it out with the DWW-6500 Double Din LCD HeadUnit. I would still like to use the controls on the steering wheel. Should I use the SWI-X Universal Steering Wheel Audio Control Interface or is there an easier/better solution? Any help would be greatly appreciated. Thank you.