I've been frustrated at how to hook my iPod to my '99 RX300 stereo. I've got the high end Nackimichi and connecting a high fidelity source like an iPod through a FM transmitter or fake cassette really s**ked. I searched all these forums and elsewhere to no avail, and talked to a varieity of car stereo shops.
Finally I found in San Diego. I pulled the radio unit out (easy) and shipped it to him, and for $250 he soldered a cable deep into the internals of the stereo. I now have a 3' cable coming out of the bottom of my dash with a 3.5mm plug on the end. It takes over the cassette deck and POW full high fidelity with my iPod jacked in.
Just thought I'd share.
Jim