From the parts Fiche:
This lock screw (1st image) must be drilled out to be removed. This bolt requires BMW Special Tool #51 0 531 (2nd image) to be installed. Found in the maingroup for tools. The tool will fit any 1/4" drive. If you would like a substitution for the lock screw, Order by Part Number 07119904102 (3rd image). Be sure to use blue Loctite as the substitution does not come with it factory applied.