I don't think the AuxMod has seen any development recently, I don't even know if it is still being used by anyone. But for the sake of argument, here is the information about the mod.
- AuxMod is a circuit board that connects to your factory stereo and makes use of the Tape/MD player
- It converts the Tape/MD player to an input port (3.5mm RCA mini)
- With this input port you can play mp3 players or anything that has a standard headphone port through the factory stereo
- Successfully tested with the RX-8, Mazda6, Mazda5, Mazda3, Miata, MPV, Tribute and Mazda2 (according to the website)
- I believe Protege 5 has been successfully tested, although no official word from the developer