fablog,
if you take apart the logitech pedal board, you will very easily see where there are 3 potentiometers, 1 for each pedal, and you will see how they are wired. So initially, I just pulled the wire spade leads and connected them to the original gas and brake pedal potentiometers. The clutch pedal wiring I covered ends with e-tape and they just aren't connected to anything. (None of the games I play use a clutch).
After awhile, the original machine pedals started acting up. Fortunately, I still had all potentiometers from the logitech setup. Pulled them out and replaced the originals. Had to use an exacto knife to cut some plastic to get them to seat properly, but it worked great and has been working great for the past couple years!