The cig lighter adapter is available from a few vendors. below is a link to Wingstuffs offering:
http://wingstuff.com/products/3622-f...ket-for-gl1800
Pop the 4 pins, rip off the side trim, and the cubby pops out. You will find the connector sitting there all lonely and the plug on the cig adapter plugs right in. On the inside front angled side of the cubby is an X (or some other mark, I can't exactly remember). Drill the hole there (I think its a 7/8" hole). Mount the cig adapter and you now have power in your cubby.
What i was suggesting above was to patch in to the connection at the cig adapter and power a small USB unit in parallel at the cig adapter. That would avoid tying up the cubby and drilling a chase for the wire to run to power the handlebar mounted phone. Either way works fine. Enjoy.