Yes, you could also use the hidden telephone cable to get power and ground. If you choose that way, here is the wiring schematic:
Then you can just run the cord under the dash and to the A-pillars, etc.
Gosh, maybe my memory is failing but I fairly sure there is a GP near the fuse panel - there is on my 997 and I thought so too on my 986. With the outer carpeted panel removed, if you pull the carpet back a little, you should see a very large bundle of wires coming down to the left of fuse panel. I recall it being tucked behind there towards the bottom... I'll try and get you a pic from my 997 this weekend where it is.
Good luck
