Ed,
there should be a "box" on the transmission tunnel deep under the dash. It will have a black plastic plate on the front. The wiring for the Radio is inside.
I fitted speakers, radio and antenna to my 2009 Roadster. I've sent you a pm with my e-mail as I wrote up the installation in detail, it is a pdf file. Send me an e-mail and I'll send the details over to you.
There is also a thread here with the details, but the search engine here is not something I get on well with!!
