Which settings are you trying to change? Currently, the TPMS sensors should show you a warning on the dash when any tire is 25% or more below the manufacturers recommended tire pressure. Are you trying to increase that percentage so you can run lower tire air pressure and not see the TPMS warning on the dash?
From what I have read with guys who have tried to disable the TPMS or change the settings, all attempts have been unsuccessful via the TechII or even going to the dealership. The most they can see on the TechII is that "TPMS on is enabled" and cannot change settings or disable.
I would not think you would be able to change setting or disable the TPMS due to being a Federal Motor Vehicle Safety Standard for all vehicle manufactures by the NHTSA.
Trying to raise/change the pressure setting on a 07 Silverado. Not my car. But the person put on bigger truck tires with 80psi and his tpms warning keeps coming on. Did some google searching and it says you can change the pressure that the tpms calls for. But can't find anything on the tech 2