Well if you have the CDR-220 or CDR-22 radio, there is an auxiliary input in the back that you can use to plug an iPod in directly. Here's the part you need:
http://www.epiqautosport.com/mode/products/prid/230/1143
This will allow you to use a direct connection to the stereo. If you want a full on iPod interface, I'd recommend the Harman/Kardon Drive+Play system. I am installing this in my 2002 S right now and so far I love it. The only things I have left are to hook up the aux connection (parts on order, using crappy FM modulator now) and to splice the power directly into the car's 12v DC (currently using the cigarette lighter).
There's also other options such as the Denison Ice>link or Monster iCruze. But if you just want a direct iPod connection, just get the cables from EPIQ and you'll be good to go.