oh, almost forgot - i just traced further the wiring for the US spec X5 -

LCM module (A3), connector X38, pin 15 - left rear fog light - comes to pin 12 on X609
LCM module (A3), connector X12, pin 1 - right rear fog light - comes to pin 10 on X609.

X609 is the trailer harness that is tucked away in the trunk - so, if you are able to pull those two signals from the pinout, you should be fine. On non-US spec cars the wires go directly from the LCM to the light bulb sockets in the rear bottom door