i've 4 manned CoT and gotten bronze drake dead with still 5 mins left so it's definitely going to be doable after 3.1, especially if DPS is upped a little. Simple trick is just to take 2-3 stacks of mage food and spam drink whenever you possibly can. I've also never ever dropped a mana totem in any heroic (I don't even have a key for it, lol), it really helps to have a easy key to pop watershield back up -- WS and Thunderstorm are a much, much bigger source of mana than spring.

chain heal is a big drain on mana, if only one person is taking damage you shouldn't really be chain healing.