If you take it slow, you can go as a group through the dungeon, hopping back and forth down and back up stairs at the entrance (if filled with spawn) and the red key level (the landing is good for healing & rezzes), slowly clearing a path (try going over traps one at a time, or synchronized as a group). Once you get to the red key area, then the hidden door becomes the refuge to dart in and out of. Eventually, if you stay in that room, with a could of tamers, one with peace, you can sit in it and farm it just like the other two rooms.
The hard part is just getting there.
Once you have multiple sets of keys, only the key-bearer has to make the run, and can IIRC do it dead, and van be rezzed across the water, to drop the keys. Everyone else can just wait there at the entrance, partied, close to the water, and the keys can be passed over the water in a couple spots.