thanks for the guide! I had the most difficulty at Step 2. It just did not want to come out and I was giving it some good elbow grease. I was afraid I would break the assembly.
Other than that, I broke one of the clips at Step 7. =X And for my custom piece, I used a pen cap, cut it down, and glued on a square piece of credit card to match the height of the original fogs. I have a 2006 330i and I can turn on the rear fogs without turning on the front. Great mod!