the CD player attaches to the tape player through some type of proprietary cable, i assume you could take the cable apart and there'd be wires inside that you could use to tap into it, but i wouldnt know which line to tap into. some people have had success with tapping into the tape input and loading a blank tape, thus the HU thinks its playing a tape but the signal would come from the ipod. (although that was a g3). honestly, if you get a good radio adapter, you peopbably won't be able to tell too much as the stock head unit is not that good to begin with. other than that, a tape adapter is your next best option. you do realize that an aftermarket head unit in the 100 dollar range can be found with aux-input, and wil sound MUCH better than the factory head unit.