I found software/hardware to flash and reprogram a PCM on our Bonnes as well as a variety of other cars! Just took a little googleing.
It'* made by a company called HP tuners and it allows for full PCM editing on 97+ Bonnevilles, right down to the binary code. I wonder if it'll work on a 96 since it'* OBD-II. I'm not sure I wanna take a gamble for 500 bucks. The site is here www.hptuners.com
But I am thinking of starting an all-encompassing GM V6 tuning shop, so it may be useful for that venture if it materializes.