2004 Saturn Ion 2 QC w/ 6 disc CD changer.

First I'm very happy with the stock stereo's performance as it's met my needs perfectly... well... almost otherwise I wouldn't be posting this. I don't use CD's anymore... like most people, I've switched to MP3's and I don't want to have to burn discs everytime to update my songs. I'd rather just plug in my iPod and be done with it. Is there a way to wire in an auxiliary input to the stock radio? I've noted there's an aux button, which, to the best of my knowledge at the moment, does absolutely nothing. I could probably splice it in myself, if I found a place to splice into. Anyone care to help?