Yes. But without a wiring diagram, it's kinda hard to show. If someone could share a diagram for the '08+ Mz5 then I could show you how to do it very clearly. The manual I have is for the '05, and according to it, the fog lights are powered with the tails.
I investigated the operation of the fog lights when I was going to hook them up as DRLs. The fog relay has 2 legs for the coil, 1 of which is has power supplied from the low beam relay, and the other from the switch on the stalk via the BCM.
The modification required is to extend 3 of the 4 of the legs of the fog relay. Take some male and female blade connectors and solder 1 of each onto both ends of a short solid wire piece just enought to raise the relay up to bring a wire off the lower left leg (from the front facing the fuse block) and keep that leg from contacting it's female couterpart in the block. This disconnects the power switched leg from the low beam circuit and gives you control of where to power it from. Reroute this leg to the tail (10A) fuse (then again, if that is still wired the same as the manual I have shows) and connect with some type of fuse tap. That's all there is to it.
If any of that makes sense, great. If not, I'll try and explain it better.
