Both are compatible, but there are other limitations.This project is becoming more awesome every update. I know you got the analogue controller working, so does this mean you could technically use the mission stick and steering wheel as well? (yes I know the Saturn wheel is garbage, but the ability to use it would still be cool)
RDC even picked up a second Mission stick to try out the twin stick configuration (stock image below...).
That would give you a total of 6 analog inputs in theory..
The Saturn wheel only has one analogue output (the wheel its self) and all driving games need 3 (steering, accelerator and brake).
I have picked up two 3rd party wheels so far, but they don't do true analogue - the pedals output digital signals, acting more like rapid fire.
I'm looking at picking up a MadCatz 'True Analog' Wheel as i have read that it emulates the 3D controller, rather than the digital controller...