Need help guys,

I have a 2008 A4 2.0TDI SE with SatNav MMI & CD Changer. I've just bought the Harman Kardon Drive and Play system to get my iPod fully mobile but I need to know how to connect it to my ICE. It says you can either do it via the aerial socket or through the aux input socket. I've removed the head unit but I can't see any sign of either,

Any ideas/experiences of this?

Cheers