Survival, Survival, Survival.
Gear for survival. Get your 21-22K HP, then go for as much avoidance as you can. You'll want 24-25K minimum HP (or a ridiculous amount of avoidance) per stomp.
I can see an Agi/Def elixir combination working, but my guild provides flasks, so I've always run with fort.
Don't worry about threat stats on Brut. Stick to your rotation, you will have infinite rage. Have a plan for every stomp. Personally I use Trinket (shadowmoon, still don't have watch), Nightmare Seed, Last stand (couple are skipped because we hold taunts until stomp goes off), and shield wall for the last one, so the healers can throw a couple smites or whatever. When you farm enough sunwell gear and have the avoidance, you can start swapping in threat pieces.
As you get more comfortable in attempts and they get longer, you can consider using Xav's idea of a threat weapon early on, build a threat lead, then switch to your mitigation/avoidance weapon.
As far as gearing in sunwell, just try to swap for more avoidance gear at this point. A lot of the gear I used when learning, and on the first kill had a lot of avoidance on the gear itself. I gemmed for avoidance on some of the gear I got in sunwell, but unless you can get yourself a second set of T6 I wouldn't regem it.
Luck is what happens when preparation meets opportunity. -Seneca
Everyone marvels at a square egg, but only the chicken understands the PAIN.