Don't know any thing about a NOSE on a BMW but.
You really don't need to remove the altenator.
If you disconnect all the electrical leads on the Alt and don't ground to pully or altenators frame you should be safe.
You can simply disconnect any thing else you are worried over or unground it. (unbolt it and put insulating material between it and the car)
Bear in mind when you are placing your ground that electricty follows the path of least resistance and copper is a better conducter than steel.