I can only post a link to this video, can't embed it here. It's a WRC.com feature on power steering but done by a member of the MINI WRC team (Teena Gade, engineer to Kris Meeke) using their parts and car. VIDEO - WRC2011: Technical feature - Power Steering
"driven by the engine" ---- The WRC car does not use an electric power steering pump. And she didn't mention there being any adjustment. Can't believe there isn't unless the FIA forbids it. Wish there was a way to turn down the assist on the street car. Too light and too little feedback for my taste.
Do you have an R56? (I can't tell, No Garage set up yet.... Hint Hint) If you do, and you have the "Sport" button, then you know with a press of the button, one of the things it does is firm up the steering. And it's doing this by communicating with the ECU. It might be possible to change the feel even more, but you will need to talk with one of the R56 tuning guy's. There are some things they can change. More so when the R56 ECU is fully cracked in the "Near"?? future.