By early June 2012, I reached Diablo III Inferno Difficulty as a Monk. With my gear focused on Dexterity, All Resistance and Armor bonus I have been able to tank pretty well through Hell difficulty, and even the early ACT I and II in Inferno. It's afterwards that things get hectic with my former build and gear stats.
In Inferno Difficulty, you really need to get gear with Vitality, All resistance, attack speed bonus, Life on Hit and Armor bonus (if gear has Fire resist and All Resistance bonus this is ideal for a Monk. Try to grab gear with the same single resistance bonus -- because you can clone it to all other resistances through a passive skill). 35,000 health is still not good enough, but manageable at times. You should aim to stack 1100+ Vitality, Life Per Hit (1300+), and 650+ All Resistances.
With the One with Everything passive skill your highest resistance stat is cloned for all your resistance types. The Mantra of Healing with the Time of Need rune increases your resistances by 20%. If you already have 650+ unbuffed, that's good. You might reach around 800+ all resistances with the two mentioned skills.
**If unbuffed you are 800+ all resistances, then it would be a good idea to free up the passive skill slot with "One with Everything" with something else.
Recently Reached Inferno
If you barely reached Inferno as Monk, your gear is low in stats and quality. Common sense. It will take you a while to get enough gold to buy from the Auction House all your new gear.
It's out of the question. You need to survive, somehow, those nasty one-shot kills from main boss events with the lack of proper gear. Here are some of my my personal experiences on how to tackle this issue until you get better gear:
Tanking Rakanoth (Inferno) as a monk is jaw-dropping when you get killed in one hit. I kept dying and dying again for days on Rakanoth. I decided to change the build I always used in Hell difficulty. That's all I needed. Rakanoth died in the first attempt after changing my build.
Here's the secret to survive Rakanoth (Inferno) as a Monk tank. There's a good Inferno Survival Monk build to stay alive long enough against Rakanoth and in certain situations.
Crippling Wave (Concussion): Enemies hit by Crippling Wave inflict 20% less damage for 3 sec. (This will help you tank without getting one-shot, and this might help other players who get hit by his skydive-like ability.)
Breath of Heaven (Penitent Flame): Enemies exposed to Breath of Heaven run away in Fear for 1.5 sec. (Helps some when you have several adds on you. Range DPS can take care of them while feared, and as a Monk tank you aren't getting those extra enemy damage hits for a few seconds)
Blinding Flash (Searing Light): Increases the chance elite enemies will miss attacks to 60%. (goodie, use it)
Inner Sanctuary (Safe Haven): You and your allies standing in the area of effect of Inner Sanctuary regenerate 1550 Life per sec. (Not only do the Soul Rippers get feared away by Inner Sanctuary, it is a second heal to the monk and nearby melee players standing on it)
Serenity (Peaceful Repose): When activated, Serenity heals you instantly for 6202-7752 Life. (Yet another heal and immune for 3 sec? Go for it, dude)
Mantra of Healing (Time of Need): Mantra of Healing also increases resistances to all damage types by 20%. (Your allies get this 20% All resistances buff too)
Resolve: Damage you deal reduces enemy damage by 25% for 2.5 sec. (So let me see: 25% damage reduction for 2.5 sec on top of the Crippling Wave+Concussion Rune inflicting 20% less damage for 3 sec and the Blinding Flash+Searing Light rune increasing the chance elite enemies miss attacks by 60% -- "I see what you did there!")
Seize the Initiative: Your Armor is increased by 100% of your Dexterity. (As stated earlier, you should stack up Armor bonus and Dexterity in your gear. This is why. Use this passive to tank)
One with Everything: Your resistance to all elements is equal to your highest elemental resistance. (All those Fire resist + All Resistance bonus in your gear is cloned toward all other resistances -- aim for 650 unbuffed to reach 800+ with the active/passive skills)
Mouse Button Setup
I have Crippling Wave (Button-1) and Breath of Heaven (Button-2) for quick healing.
Active Skill Rotation
Always have a stack of 60 Mythic Health pots with you before starting the boss event.
1. I usually start with Blinding Flash (15 sec) to increase elites' miss attack by 60%. 2. Got your health down a bit? Drink a Mythic Health Potion (12,500 Health / 30 sec cooldown) 3. Next time you get damage, hit Serenity (immune for 3 sec, and heals you instantly for 6202-7752 Life). 4. Maybe Blinding Flash cooldown is over. Hit it again. 5. Next time you get damaged, hit Button-2: Breath of Heaven (15 sec). 6. Next time you get damage, hit Inner Sanctuary to get a renew heal (1550 Life per sec) 7. The Mythic Health Potion's 30 cooldown is hopefully over by now. Watch cooldowns of all other abilities that can heal you up. Kite a bit where needed until cooldowns are over for the next heal.
It would be good if all players stack behind you when the dogs spawn. Your Crippling Wave does damage to them, your Inner Sanctuary heals players over time and your Breath of Heaven also heals nearby players. Better for your coop team than running all around the place trying to flee from the dog minions. Of course, fighting the dogs near the Monk tank means they get feared by Inner Sanctuary and Breath of Heaven, and the dogs also get the "chance for elites to miss attacks by 60%" from Blinding Flash. Win-Win.
I tried the same Monk build of Rakanoth against Izual. However, Izual can't be tanked. He will one-shot you. He aggros by proximity. The player closer to him will be chased down by Izual.
This boss is more about kiting, and if you can't melee -- that means you, as a monk, can't regenerate spirit. If you attempt to hit him a couple times to regenerate you will die. Proven fact 100% of the time.
I made a change to the Rakanoth build. Since this boss is mostly melee damage, the all resistances passive skill is moot. Change the "One with Everything" passive skill slot to "Chant Resonance" to increase Mantra of Healing duration to 7 minutes and to get 2 spirit per second -- which is helpful with all the kiting downtime.
So what's the Monk's function then? You kite Izual while ranged DPS players pew-pew. All you have to do is run around the western-most circle. All ranged DPS hit him from the right side as far as possible from the southwestern circle so he doesn't aggro away from the monk.
What's the 2 spirit generation passive skill good for? Because you are the one kiting and out of harm's way, you are also on Resurrecting players duty. When a player dies near the circle you are kiting him (southwestern-most circle) place an Inner Sanctuary on the chokepoint and keep walking south. Izual won't be able to move forward, and he will stay there because he's aiming in your direction.
This will give people time to resurrect a player, or allows the monk to get Izual off his back long enough to allow resurrecting another player. If everyone dies when the four minions spawn, you can use that same technique with Inner Sanctuary on a chokepoint to flee away -- giving you time to resurrect a player.
As you can see from this strategy, with non-Inferno quality gear the Monk is useless as a tank. However, with this build you can be a good kiting bait, and allows you time to help with resurrections.
Update: Killed Izual with this build -- mostly utility duty blocking chokepoints with Inner Sanctuary, blinding flash at key moments, and resurrecting-other-players duty.