I have been looking for this same cable. I have done some research, and found some info on the RAV4 forum. This particular fellow, gutted a Scion that was wrecked, and removed the cable. Everything worked great after that (except for the Scion).
Check the sc12234 part on
ebay. It goes from the head unit to ??
I am currently using the USA Spec PA11-TOY interface. The connection is great; but control is best done via the iPod, not the stereo head unit.