Short answer; the tranny can be controlled in such a manner.
LOng answer; it takes some parts.
Early (1997-98) previous gen GPs had a sport shift button on the shifter that changed shift points. Later (2000-2003 for sure) did not, BUT, depending on year, all have the light in the dash, an dsom ehave the harness already under the shifter, just need teh button and new knob, some need new or reflashed ecu. (can't find it right now)
An ecu, I believe , would have to be set to allow manual control, but other than that it would be harness only and shifter. Because of the liability involved I would be very hesitant to replace the steering wheel and harness of teh column with teh air bag in the way. That would definitely take a professional. I would not be above replacing a stick and brackets along with its additional mounted switches that are what give you the manual control.
__________________
When more than one friend wants to ride shotgun

No, I
do not work for GM,
but if I did, the G8 ST would not be DOA!