You can't rent it at the mountain.
You can get it at EMS for one. Here was the deal today, at 10:15 I was told I couldn't get in without avi gear, but that they may reavaluate later. About an hour later they where allowing skiers and riders in without. There was waist deep in spots, but had to be very careful of waterfall and other obs. as there is alot of ice blocks in there too. It was still puking snow when we left around four. Tomorrow should be another great day.