They are unmezzable anyways so a chanty friend won't help. What we ended up doing was after we got the mission, we split our group into two groups instead of one, and broke out a couple cleric mercs and a warrior merc. Group consisted of Pally, Ranger Shaman, 2x cleric mercs (tier4,tier3?) in one group and Beast, Enchanter, Wizard, Clerc Merc (tier1), Warrior Merc (tier1) in the other group. Group 2 were all boxed and ranger/shaman was boxed.
The plan was to have the warrior merc tank some and I tank some, while dps did thier thing, but it didn't quite go as planned. I believe the warrior Merc died right away (stupid guy ran up and got creamed
) but we just DPS'ed them down. Ranger and Beasty traded aggro on the two mobs while I played with the other 2 until they finally killed thiers. It was pretty ugly but we made it through.