Aux input help needed

[SWATH2]

So I'm pretty handy at installing things in my X5, having already completed a BSW Stage .75 (fronts and sub/amp). I want to add the auxiliary input so I can use my MP3 player. Simple enough right?

I bought the suitable cable for my 2004 X5 (Non-Nav/DSP) and got ready for a quick install. Big surprise when I pulled the radio out to check the connection! None of the diagrams supplied by BMW match what I have. I have the black twelve pin connector, but the spaces they say to attach the AUX cable are already in use, and I don't have any other input besides the stock CD as listed in the instructions.

Anybody have an idea what where to go from here? I'd really like to complete the install myself without having to pay installer rates fro a couple of wires.
Thanks