This doesn't look too hard. I snapped one of the release buttons off on the data cable and used that to pry off the case. Underneath it looks like this:
If I were to label the pins starting at pin 0 and going to pin 16, then pin 0 is black, 3 is blue, 4 is white, and 5 is red. (all corosponding to a pin on the usb cable).
If I were to wire services into the cable, then I would connect pin 2 and and 16 to the charge cable (I bet #2 is grounded). I have a friend with a steady soldering hand so I'll have him do it.
Anybody know the pinouts that a nexttel serial cable uses? I bet I could make a serial cable myself. This means... serial NEMA GPS output!