Adjust as per manual. Then run each diff in by applying partial throttle with one pair of wheels (left or right, it doesn't matter) on the ground and the other pair lifted off the ground. Do this for about 15 second then readjust the diffs.
Recheck the adjustment after the first run.
If you don't run the diffs in you will end up with the diff backing off as the parts seat.
This applies to any car, not just the tc3.