I recommend using the max-range trick on eck, tank him right in the arch into his cave and have your shaman stand about 30 yards out on the top of the mound with the ribcage sticking out of it. Removes the need to taunt, since eck never attacks anyone but the tank.

Edit: the first time i did this i made sure i started tanking him at about 40 yards and slowly brought him back until the dps started landing spells (the heals all have higher range, so it's a safe way to judge it without dying before you find the right spot)