In the thread about the original Palm3 GPS unit being on sale at Staples, there was a link to a picture of the Palm docking connector pinouts. That's what I used.

And when I opened the GPS to do the soldering, my only question was orientation... which pin was pin 1? I mean, I knew from the connector docs, but I wanted to be certain. Turns out that once I had the GPS open it was dead obvious which end was the ground pin (you know how on PC boards the big flat areas around the outside edge are ground), so that was a no-brainer once I had it open.