to come off to get at the adjustments.
In the factory manual (of my Turbo) about all I could find was that if the headlight bracket needs to be replaced to use the old bracket's adjustments to set the new bracket's adjustments.
When I got my Turbo back from the body shop the passenger side headlight (replaced along with the bracket and in fact the passenger side fender) the headlight was obviously not positioned correctly. The beam may have been ok but the headlight's fit did not match that of the other side (undamaged and factory). I took the car back to the body shop and it took the car to the dealer and had the dealer's tech adjust the bracket to position the headlight so the headlight fit just like the other side and the light beam was properly aimed.
Let me see if I can find out anything specific to the Boxster in my references. But I suspect you will probably end up having to take the car in to a qualified shop and have this done.
Sincerely,
MarcW.