REQUIRES TANK QUEST!
If you have the tank quest in Grimvault, you can use it to solo the 5 man bounty quest. You can summon your tank (Press T) from the hill since it is the required area and pull the elite with your tank (Or pull him and run to the tank summon area perhaps?) and use ability nr. 2 to kill him.
I am a bit unsure of the pulling part since I was in the tank when somebody else had pulled him and was running away. Either way I could hit him with the tank for massive damage. I two-shotted him with it.
EDIT Seems like you can pull him yourself if you come from the correct side, since he is standing in the required area "Desolate Highlands"
THIS HAS NOW BEEN PATCHED AND NO LONGER WORKS