This is gonna sound like cheating, and it is, but not by the games definitions for some reason.
If you group with someone higher level to you and they mentor you, the mobs will all con according to the other persons level. This works in two ways for you. One, if you still agro, you get credit for their kills towards your quest. Second, if you dont still agro the room, you can now walk/sneak in accordingly and not worry about the rest of the room, once again, according to the other person(s) level.
I don't particularly agree with this, but I have found that it works, and not just for this quest, but others if specific mobs are needed.
Just seems like a way to 'twink' your friends if you ask me, but HEY! its your game, play it like you want to.
Good luck ...