Haven't tried it with a mage, but an 80 paladin can pull the whole joint at once. Leave party at the entrance, only pull the boss at first. Then I run out to one side on the top level, go about 3/4 of the way down the "corridor", then jump off into the bushes. That way, they will run to the end and it will buy you some time to run to the other side and repeat. Then before you go to the lower level, run to the waterfall making sure most of them are close to you. Jump, bandage/heal while they run the long way around, then grab whatever you can on the lower level. I usually have them follow me into the 1st hallway so my team can heal or help out with aoe to speed things up.

I didn't come up with this myself, just got the idea watching youtube and reading forums.

I think a frost mage has some tools to slow mobs down so that might help. Oh, and I do use speed enchants on my boots, does help a little.

And running cath+armory is the way to get around the instance/hr limit. Though after say level 36 or so, armory gives low xp. Around 38-39, same for cath.