The best class to do this with is a level 70 warlock. It will involve DoTing and then using pathing exploits within the instance to down trash/boss mobs.
http://video.google.com/videoplay?docid=-8640617637006519726
Above is a link showing it in action.
It might be possible with a shadow priest as well but will take much, much longer to down the mobs.
Short version:
1. Trinket, SB, DoT
2. Move to other pathing, mobs change direction.
3. Reapply DoTs as needed, drain, cast instants.
4. Mobs re-approach, move to previous location and repeat step 3.
5. Loot, move on, pull mobs back to bugged path.
Long Version:
The first pathing bug is along the river between the 2 lanterns. Stand on the center land between the 2 lanterns but make sure you're a little to the right. Wait for the patrol to pat to the right of you along the river, trinket up and hit them with a big hitting spell. They will approach you from the right. As they aggro, strafe left so that you are "unreachable" by the mobs, They will follow the new path to get to you. Careful they come pretty quick. Spam your dots and instants while jumping back to the right side of the water. They will turn around and come from the right again, jump left. rinse / repeat DoTing the whole time.
It will take some practice to find the boundaries of the pathing.
Avoid as many mobs as possible in the open area. Be extra careful as their aggro range is much higher on heroic (lvl 70 elite).
Second pathing exploit will be on the right side of the tunnel entrance as shown in the video. Stay to the right so you don't aggro the 2 guards. Have your imp stop in front of the guards (not in aggro range of course) while you go to the back wall.
Target the guard and have the imp attack it. You can choose to summon another one as soon as you can. The mobs will be bearing down on you though and it's imperative that you jump onto the ledge to your right. You, again, will be unreachable. So do your DoTs and instants. The mobs have to path a little longer so you can afford to cast a few longer casted spells.
Don't forget to keep tapping for mana while siphon is up.
You will pull the first miniboss to this area as well. He will hit you so use drain life and siphon to keep yourself up. He drops a badge of justice, yay.
Other classes will have some difficulty pulling at this spot since they do not have a pet. If you're a shadowpriest you may need to use an inuln pot, or maybe a swiftness potion+bubble.
Note: The video does NOT show some of the 5 pulls later on in the instance.
I also did not make the video or take credit for it. I have not seen this posted so sorry if it has been put up before. Give it a shot all you warlocks it is really fun during offpeak times when there are no groups to be had.