yes your right the sizes of the sockets dont seem to work, lucky that i had a 1/4 socket mini system that worked well. I would almost think your better off loosening the housing for the cpu (the plastic black box) on the passenger side fender. This would give you more space on the front of the engine.

Your almost better off taking the power steering pump too and the roller plate which holds all that on.

There are 3 bolts for the alternator unit and some of the bolts are on the front of the engine and the others on the other side.

For a well designed car, i really feel this part of it was overlooked as it took me a few hours replace the unit on my 850.