Cheers guys I didn't think I would get as good a response as I have done. Nice one. The reason I ask is that I saw a cd changer to Ipod thing as part of a headunit lot on ebay so thought it must be possible somehow.
Ian thats what my brother thought you would need, he is one of these electronic types

He knew that you would need something to tell the headunit that there was an Aux in waiting to be used through the pre outs. I would have just brought a cable like in your second link and expected it to work.

Thanks Ian
Aceraf I brought my misses one of those and found it crackly at best on her lesser spec cd headunit, although I haven't tried it on mine, I am not too hopeful! I shall try it tomorrow.
Choppa, stupidly I didn't state that my headunit was a cd player(although some guessed due to the model number) so your solution won't work on mine
Cheers for the help, i'll investigate the transmitter, then probably buy something like what Ian has posted if its rubbish.