i did this on my e36 and i used a wrench to get it off, and actually when i was putting it back on(well the guy who was helping me, actually) was even able to get a ratchet and socket on there, there is no reason to try to come from the top
EDIT: and yes, for the wrench, it took me FOREVER. there is barely any room, but slowly and steadily it can be done, and there is something called a crowfoot, where its like a wrench except you hook up a ratchet to it, it helps sometimes but can still be a pain