So getting access is just a matter of removing the side cover and is the rest pretty straight forward? No fluid drain? No axle pulls? Not really worried about tackling such a job as I have been doing my own mechanic work for 20 years, I just don't like surprises.
On another note, the speedo has never acted up and I keep reading that the speedo should stop responding when the transmission acts up. There is reference to the TPS may be causing the transmission issues. The only thing is that I got a code P0716 and I replaced the output speed sensor and had the code erased. The transmission has acted up again but no check engine light has come back on. I am going to take it back by the parts store and have the codes checked again.
I searched ebay and found the following link, but not sure if it is worth the $35.
eBay Motors: Pontiac Bonneville Service Repair Manual 02 03 04 05 (item 130299401018 end time Apr-15-09 14:44:33 PDT)
I also found a link using what you specified and found:
eBay Motors: ATSG TECH MANUAL 4T65E 4T65-E 1997-ON GM ELECTRONIC (item 350161644639 end time May-03-09 18:53:05 PDT)
I have a Haynes manual which is great for general info, not so great for precise instructions. It doesn't even mention the Input speed sensor.