I installed an iPod2Car adapter this summer in my 2002. Here's what you need: (1) Peripheral iPod GM Interface Kit (#5411SGM73) and (2) Peripheral Car Cable Adapter (#541GMH20TC). These can be obtained from Crutchfield. I got mine locally.
Using this combination you do not need to access the passenger foot well. Remove your factory head unit and disconnect the factory harness. The adapter cable has three ends. Connect one end of the cable adapter to the head unit. The 2nd end to the cable included in the kit (1 above). The 3rd end to the factory harness. The cable from the kit connects to the iPod2Car box. The last cable connects between the iPod2Car box and your iPod. Lastly, set switches 3 and 8 to ON on the iPod2Car box.
The installation is really easy. This
link describes what I just did plus has pictures of the cables and where they connect.
Sometimes my Bose head unit will not recognize my iPod when I connect it. I believe this is occurring, because I use a different iPod interface in another vehicle. The iPod gets confused when switching between vehicles. To fix this I have to reboot my iPod. This resolves the problem and the iPod works without further issue.
Rebooting iPod:
1. Toggle the Hold switch on and off. (Slide it to Hold, then turn it off again.)
2. Press and hold the Menu and Center (Select) buttons simultaneously until the Apple logo appears, about 6 to 8 seconds. You may need to repeat this step.