I love tanking H-HoR as a warrior, as in my mind it shows off all our utility.
First, I don't tank in the alcove. I find it silly.
Have the healers/ranged dps hang back by the gate that drops down once you start the encounter. Tank the mobs around the edge of that initial hallway right where it enters the room. Charge the nearest mob that spawns (tip: you can click target them while they are channeling, but tab won't pick them up then) then pull back to the center to Thunderclap and pick up any of the other melee mobs. Once you have the melee mobs in a group Shockwave. While they are stunned, target any ranged mobs that are up. If it's a mage, just use Heroic Throw (if you don't have 2 pts in Gag Order, shame on you! /grin) and toss a taunt for good measure. If it's a hunter, charge/intercept over to it and disarm (it removes their gun) and then move back to the main pack. Once you've got them all in a group it's the usual: cleave, thunderclap, shockwave, revenge, tab, etc.
All that said, the SINGLE most critical thing for success in H-HoR is the kill order. DPS should NOT just aoe everything down. Priests need to die first and as fast as possible. Then Mercs. All dps should be single targeting these down asap. After that it's less critical, but I like to make sure that the mages are NOT the last mob to die. The reason is that when they do their mirror image, if you kill the primary mage first the next wave can spawn while you're still burning down the mirror image. But in summary, aoe dps on the initial waves before the first bosses is bad. You'll take too long to kill them.
"What we need is a special blend of Psychology and extreme violence"