I did this job on a 2006 330xi using the following guide:
Replacing BMW E46 front differential seal
The guide (E46) and my car (E90) were identical. I've found so many other things identical or similar with the E70 so there's a good chance it's the same as well. At the very least the process will be same as almost any car.
The most important thing is to make a punch mark on the flange nut and shaft so that when you put it back together you can tighten the nut to the same spot as it was before. This is very important to keep the factory adjustment. You don't really need to worry about counting revolutions to remove the nut because when putting it back on, one turn too few and it's obviously too loose and you'd have to be a bear to go one extra turn, if it's even possible at all with home tools. I used an impact gun to both remove and re-install the nut and it took a bit of power to finally get it back into its original position. (i.e. I had about 15 degrees more to tighten and needed to up the power of the impact gun to get it there)
Overall it turned out to not be a terribly difficult job to do. Good luck!