As noted on Bimmerfest, I'm so close to getting a successful retrofit.
The Light Control Module for the X3 is located under the steering wheel column. One only has to remove the plastic panel (3 screws and a plastic turn-screw) under the steering wheel to access it.
It would be extremely helpful, if someone could remove the connectors and see which pin# location the rear foglamps plug into for the X3. I tried pin #49 (as is for a E46) but no electricity flows through the connector when I hit the button to switch them on.
I followed these instructions, skip to the bottom to see how to remove the LCM connector plug.
Diy: Oem "rear Fog Light" Retrofit! - E46Fanatics
It's the last step! I've got the wiring done.