I don't own Evo 4x4 myself, but I assume that it has a Gamesprockets configuration window.
Does the steering wheel show up in the window? If not (and not knowing anything about your hardware or your application software), here are some suggestions:
1.) Download and install the latest version of Gamesprockets (1.7.5), if you have not already done so. You can get Gamesprockets from:
http://asu.info.apple.com
2.) Rebuild your desktop so that your computer can locate your steering- wheel extensions and activate them.
With any luck, doing the above two things will make your steering wheel work with Evo 4x4.
Hope this helps a little.
Tristan