Interfacing iPod w/OEM HU

Hi everybody. I'm planning to interface my iPod with my head unit using my cd changer audio inputs, not the m-bus interface. What I'm trying to find out is how to "trick" the HU into thinking it has a changer plugged in. Does it just know that the changer is plugged in by sensing the closed circuit with power connected? Or does the M-bus really need to communicate with it's own special protocol?

This guy did it with his HU(not land rover). http://www.geocities.com/blhobbs.rm/Mazda_stereo.html

If anyone could enlighten me on this type of a hack, please let me know. BTW, before everyone tells me, I'm not interested in the many overpriced interface boxes out there.

Thanks!

my buddy has an ipod with a deal that plugs into the cigarrette lighter and plays off of various fm stations, or is that the interface you are talking about?

The sound quality is sh!t when you listen to it through FM. I mean, it's ok, but not good enough. I know that's the quick fix, but oh well. I'll do it the hard way, as usual.

Daniel