So in my recent discovery of this page, I have been able to trace any and all wires that i need to perform a DME change as well as create a pedal harness to retrofit in all the cool 330 stuff that my 328 doesn't have.
Here it is:
http://www.bmw-planet.com/diagrams/r.../e46/index.htm
Within you can search through every harness, every bus, every module, and anything you want to know electronically about the car.
Enjoy it.