You need to ask the dealer for the iPod led when you pick up the car. (They used to charge £15 for it but I think most deaers were giving them away anyway and they took the price ticket off.) Fortunately I remembered when I was picking up my car, and my dealer just said, OK, I'll just go get you one. Otherwise I'd be stuck with the USB thing as well.
Go back and ask for one.
Rolfe.