Well, I installed the PAC AAI-MAZ last night. It connects through the CD changer port, so the stereo treats the aux port like a CD changer. It doesn't provide any sort of controls that I noticed when using my MP3 player or Garmin Nuvi as the source. It's a simple upgrade if all you want is an aux port.
This morning I did a little more searching and found an even cheaper alternative from GROM Audio. I found a vendor on Google shopping and bought one for about $30 less than the PAC AAI-MAZ. GROM Audio also has iPod interfaces cheaper than I've seen elsewhere. I'll update this thread after I install the GROM Audio aux port into my wife's 6 wagon.