Anyone interested in doing this as a 5 boxer, the twin fight was the worst, but I took my 4DKs and my paladin in, and had my holy pally on one side, with my DKs on the other, all blood spec.

I targeted the twin closest to my DKs at all times, so they would IWT with that target and guarantee they get aggro, and then i made a simple /cast [@mouseover] Exorcism macro for my paladin, and just hovered my mouse over the twin nex to my paladin. this is sometimes tricky to accomplish, and I wiped twice figuring out how to make it work, but if you are interested, thats the best way I found with a melee team. the rest of the fights are very trivial at 85, even C'Thun.