Recently did this quest and ran into the reset troubles that have been documented here. I figured I'd try to add my perspective on what was going on, in the hopes it truly is what was going wrong and helps someone complete it.
What seemed to be happening was that the npcs that aid you get reset periodically throughout the fight - possibly because they got petrified and then unpetrified from the slam, but it's more likely that that's only part of what's going on. And, when one of the npcs resets while holding aggro on the boss, the boss himself also resets.
Regardless of if the above is correct, I was able to get around the resetting issue by doing two things. First, I aggroed him immediately at the portal as he spawned, instead of near the line of npcs like I was doing on my tries that ended with the boss resetting. Second, I taunted every single time he was taunted by any of the npcs, and I also threw in taunts when they would stun him.
I don't know that my guess about him resetting on an npc reset was true, but the only attempt where I held aggro the whole time ended in me managing to kill him.
For those with pets that can taunt, I don't see why their taunt wouldn't let you complete this in the same way. For those without any form of taunt, he is vulnerable to being stunned, so you should be able to stun him through the npc taunts and keep aggro on yourself. Living through having aggro the whole time is another issue entirely, however.
In any case, I hope this helps someone. Good luck with this annoying bastard.