I don't know if this is too late for you, but here's an answer anyway.
Pop off the left trunk cover thing, and look for some groups of wires towards the wheel well, they will be wrapped up at the end by about 4 inches of black fabric. Those are the CD changer and telephone wires. Phone wire group has a brown wire in it. I have a BSW Soundplicity, which uses both of these. I dont know about DICE though.