There are generally two methods of getting data from a wheel type device. One is to attach a potentiometer to the wheel and then the computer reads the resistance to figure out how far the wheel has been turned. The second uses a rotary encoder similar to those found in a mouse. I'm not really sure which an arcade steering wheel would use, but if it's the former, then it's pretty easy to attach to a PC as long as it has a gameport. Gameport joysticks work on the same principle so as long as the total resistance of the potentiometer is about the same as a standard joystick, you would just have to attach it to the right pins of your gameport.
If it uses a rotary encoder (which is more likely) you'd have to either write a custom driver, or get one of those programmable USB interface chips.
