If your really want no tank, take 3 mages and 1 warlock.
Let the warlock put 2 points in pyroclasm in the destruction tree.
This way when your aoe you have 26% chance to stun anyone who gets hit.
For example 1x hellfire and 3 arcane explosion
Perhaps 1 a 2 holy nova's from the priest and the weak trash is dead in couple seconds. The elite can be picked up by the warlock pet
A macro for the priest perhaps to spam the warlock pet with a small heal