I had a similar problem earlier in the week. What I did (with some good advice) was wire right into the fuse panel by the driver side door. I took a male connector (flat one) and plugged it into the slot just under the 10 amp fuse on the far left side of the fuse panel (there is no fuse plugged into it, and it is labeled "IGN" on the fuse location diagram on the panel.
This will give you 12V access. Hope this helps.
2008 C6 Coupe 1LT M6 Airaid CAI, Borla ATAK catback