I have dualspeced BM for old dungeon running. I haven't gotten much of a chance to do it (because figuring out end game loot is complicated and um, the loot gods love me this week), but I figured I would share the resources I've found. And if I ever find good video walkthroughs, I'll be sure to let you guys know. There are great wotlk videos over at tank spot, and your group will be impressed if you have some clue as to strategy your first time in.
That's my current BM spec. I mostly just took talents that looked good, so take it with a grain of salt. I'm currently using my trusty warp stalker Boo, because I love him. I'm not glyphed yet, but I know I'll be looking for mend pet, feign death, and mending.
This might be better with this as a tenacity pet spec.
Any tenacity pet will work for easier content. If you want to solo heroic Magister's terrace or Onyxia or AQ 40 you may need to do some careful thinking (and gear selection). A turtle's armor bonus would come in very handy for that, especially if you're needing to do the complicated pet tanking (aka passing off aggro between you and your pet). I have never done complicated pet tanking, but as I understand it, you pull aggro off the pet, use deterance, then misdirect back onto the pet. That's a bit more than I'm willing to handle atm, but it apparently works quite well.
Your gear selection also becomes important. If you know that you're going to be facing a ton of fire damage, fire resist gear. I generally equip my alchemist's stone trinket because of the extra stamina it gives me. And of course, bandages, potions, and buff food are all really useful things to have. I don't hit a dungeon without them, personally.
Probably the best thing you can do is hit wowwiki or wowhead and read up on the dungeon you're planning to go into ahead of time. Make sure you know what types of damage you're likely to run into, and have some vague sense of boss strategy.
Elitist Jerks has a really useful thread on this subject, complete with boss strategies and gear suggestions. Me, I may try to convince the holy priest (and mount and pet collector) that she and I should duo things I haven't seen before. Say the raid with the red tiger and the raptor mounts, for example.
Oh, and while I'm thinking about it....
If you are like me and fail at pet management, grab a wolf. There's some lvl 80s in the Storm Peaks, and furious howl goes off even in passive. So even if your pet is glued to your side, they're still giving you a nice buff. Last night my dps increase from that completely offset the loss of pet damage.