Don’t worry about MFS or BSC in the name of the parameter, it is a technical trick. When you set a value of alpha in one cell it is actually copied in the MFS DB too. It’s automatic.
So set alpha to 0 means that you deactivate the UL PC in GPRS. But no impact on UL PC in GSM.
Set GAMMA TNx to the max value. If you set it to zero, it means the MS will emit at minimum power (0dB)
There also, this is a dedicated GPRS parameter, it will not impact the GSM PC.