I usually go PLD/DRK. Seems to generate the most enmity so the nuke happy blms can just go nuts when it hits the air. Every air/ground rotation it takes about 12-15% off, and if mages start getting low on mp or overwhelmed with adds, can do a double ele-sleep on the ground and just poke it with shield bash or something as soon as its time to fly. Otherwise when it wakes up from its ele sleep the tanks can take 3-4 hits before it goes airborne again.

For the adds we use brd/bst. Charm the worms and keep the ele's asleep for about 5 min till the blms get around to nuking them down.

One thing I would suggest is at least for your first try, have a couple emergency mistmelts handy. If he gets too nasty and you need to sleep him asap, you can bring him down and sleep right away.