I've only just read this thread, did anyone find a solution yet?
My wife has the S3 today so I'll take a better look tomorrow but maybe there's an answer without vagcom. A couple of years ago I was working for a rally team and we bought two new Iveco vans with fly by wire throttles. Left foot braking in them was a must if say you were catching someone on a long uphill drag on the motorway when fully loaded and towing a car trailer cos if you lifted off it dropped the boost and you'd not recover until you got over the hill. A little gentle left foot braking could be the difference between 55mph and 25mph!
The Iveco has two switches on the brake pedal, one for the brake lights, another to the ECU, it was simply a case of pulling the ECU switch connection and jumping the wires to show closed contact and all was OK. The Audi must have similar as the brake lights are hard wired to work even with the ignition off, there must be a second ECU input which could be disconnected.
2001 S3|Ebony Black|Revo|MTM Clutch|RS4 Reps|Tarox Brakes
'95 Corrado VR6|Classic Green|Koni/Eibach|Undergoing major rebuild!