Hi Gtthree
i'm trying to upload some of the pictures, hopefully they go through
essentially what you have is the factory loom which comes to a terminus just next to the gear selector lever
from memory, this then splits to the cigarette lighter inbetween the cup holders
i spliced into this little short bit as later on that can be replaced on its own if necessary
for the socket - the bmw dealer got me the cigarette lighter socket, the contacts and the plug housing - just using some ordinary automotive wiring or any other good thick gauge wiring - ideally colour coded and your good to.
literally is as easy tapping in and thats it. i dont really like the wire taps, as they can fail and dont give as secure a connection...
good luck! any questions just ask, happy to help. one of the best, cheapest and easiest mods ive ever done to a car and one of the most useful!