http://www.ebay.co.uk/itm/Sony-CDX-4160 ... 0796237886
I have found a wiring diagram, and noticed it has a 3.5mm jack for a remote on the back. Would this work as an aux-in!? (doubt it but thought it's worth an ask. If not, are there any other options before I spend money on a new stereo (other than a fm transmitter).

I was hoping a neat little box like these connects2 would maybe do the trick?
http://www.connects2.co.uk/c2search.aspx?catID=44
Any help appreciated!