I had same car
Ii has been awhile now, but I remember popping out a flat plate at back of the glovebox area. I found a wrapped fiberoptic cable bound by yellow tape...? Unwrapping allowed me to connect my BMW iPod adapter kit (used a plastic zip strap to hold it up in the cavity where CDC would have been secured) where the stock CDC would have gone. My car did not come with the CDC - just the Prep - so I ended up taking it to dealer to have it coded, worked great! Somewhere (do a search) on the forum is a DIY with photos that shows you what to do to connect the CDC. You can go from that to hook up your Dennison instead, I'll bet... Good luck!
2007 650i 0440/LCGE, 6MT, Sport, Nav, HUD, NiVi, L7, HD Radio (now from CIC), SiriusXM. Coding: lawyer screen (CIC), Halogen DRLs on with high beams (LMA), fan speed LED seen on "auto" (with an LCI-IHKA), turn signals in HUD (CIC), etc... Status: CIC retrofit complete. E90.SSD >E90-E60 merged CIC.trc >coded for Combox. To do: ICOM/WinKFP >CIC (63, 62, A0) >v41 >complete 6NR/6NF coding.