JD,
There is a 2-positions "Maintainer socket" on the s2r. You can find it on your electrical diagram. Number 19 on my 06 model. I'm pretty sure it will be the same for 08 models if Ducati hasn't removed it to save a few $$. I know it's not on the s4rs
According to 06 s2r electrical diagram:
pos1 = 12VDC direct feed from battery
pos2 = Ground
You might want to put a volt meter to double check.
The connector is a direct LIVE off the battery. IF you plug into it make sure you have a way to power off the GPS unit or make sure it has some sort of a power saving mode. Cause it will drain your battery even if the bike is keyed off.
I'm not exactly sure on its location, but I'm going to guess under the tank. According to the electrical diagram it's a female and a dummy male connector housing to keep dirt and moisture out. You can reuse the Male housing. You'll need the male pins for it so that it mates with the LIVE female bit. PM me and i'll be more then happy to send you a few of the pins. I have plenty for this family of connector.