Not the E70 X5, but may be useful or give you some ideas -
BMW - The Infamous Alternator Bracket Oil Leak on the E65 BMW 7-Series - Pelican Parts Technical Article
Might check to see if there is an oil leak around the alternator bracket while you are under there. If the car has an oil cooler the job is much better/easier, if you do not have an oil cooler, well read carefully, I think there is an issue with access to a bolt or to get the bracket out of the way.