What my group did was very simple... We managed to do it in 2 tries. What we did was we cleared to first boss without killing the critters (for a reason).
Our group comp was
Feral druid
Prot warrior (me)
Resto druid
Assassination Rogue
Ret pally
What i did, as the warrior, was (using a system of macros) shoot the watcher in the middle, Heroic throw the one on the right, and body pull the one on the left. I used bloodrage (for small amounts of initial aggro).I then intervened the feral druid (stealthed), Charged a spider, and intercepted a roach. This got me halfway up the hallway with the adds. I then turned around, Shield wall + shield block, when that ended, last stand + enraged regen and popped both trinkets, stoneform (since i'm a dwarf), and potted. I lasted about 40 seconds with all the adds on me. Shockwave is your friend, since they all are stunnable. While i did this, the feral druid tanked the boss while everyone else dpsed their brains out. Once i died, the adds started running back towards the group, and since the boss was dead, both druids shadowmelded and the rogue vanished, leaving the poor ret pally to die XD.
Basically, kite to entrance and live for as long as possible
. I've done it for 4 separate groups using this strategy.
Good luck ^.^
kinda like that approach tbh