GFHB has finally been solved for the US F15's (and a bunch of other models). Check out this thread over on Bimmerfest, there is a reference guide for the F15 with the specific coding instructions. The final piece of the puzzle was figuring out that we needed to decode the cornering light variables since the US cars don't have those. I've tried it out on our car and it is definitely working now. Kudos to everyone who has been working on this for months and didn't give up! I'm still not sure how they isolated the individual bytes in the LHM module that control the cornering lights, but they did it.
Check it out!
http://www.bimmerfest.com/forums/showpost.php?p=9430612