When I did mine I unbolted the bracket and compressor assembly and had the compressor hanging by support wiring. Unfortunately I can't remember the exact manner in which I removed the bolt, but I did just use either a ratchet/socket or a flat/crescent wrench. I know all about impossible to reach bolts having previously owned an MKII GTI 16v where most everything normally simple on cars was blind/difficult without a lift. So all I can say is just feel for the bolt first, get a tool on it however you can and try to not get frustrated. Sorry I don't have better advice on this one, maybe someone else can add to this, happy wrenching.