Don't know if you've ever heard of this outfit www.xcarlink.co.uk
or not, but if you have a look, they have both ipod and SD/USB interfaces which plug into the autochanger connector on most OEM radios. I had an SD card one on my Picasso for three years and it was excellent. I haven't got one for the CMax as yet as mine actually has an AUX input. If the car you are considering has either the 6000CD or 6000CDC head unit, it should have an aux socket in the centre console next to the 12V (Cig lighter) socket.
If you have a look on the xcarlink site, and look at the "Compatibility" tab, you'll see that both the radios shown have an "aux" button. Whether this is actually connected to something in all models I couldn't say, Perhaps one of the other older hands will know for sure.
I can definitely recommend an XCarlink for your ipod though.