Well, I'm using a tank spec personally. It might be slower than a dps rotation and spec, but I don't die (save for those unfortunate caster pats and I'm not around the comp to make it DG something to me) and it goes slow enough that I dont get the "entered too many instances" thing. I have it set to use no mount, 100 loot radius, uh 25 pull radius I think, and what CC are you using trozen? I am using Singular for my Blood DK since the targeting/facing/movement is pretty necessary in there.
I'm no wizard with HB that's for sure lol, but if other ret pallies are doing it, it might just be one or two settings that need tweaking? I should try it on my ret and see how it goes but her gear is lacking ... can't win any dang RF loot so I'm afraid she'd get beaten kinda easily to give you a head's up :-\