I have no real trouble tanking it on my lv. 99 DK as long as I take one pull at a time. Double pull can be a wipe if both CDs aren't up. Double bogstrok packs or double eredar mean you die no matter what, hope the rest of the party can finish them off and rez you, the damage is quite insane there, but it's just TW being TW.
Make sure the disease is always up, it gives you lifesteal. Pop vamp blood every time you start dropping, the CD is short. Use all your double runes on marrowrend, those charges pop fast in TW.
And most important tip for a struggling/leveling/undergeared tank: remember you basically have a pally stun now. Stunning one of the damaging mobs for a few seconds can make all the difference, I pretty much use it on CD on any pull bigger than 3.