It is perfectly doable, I have farmed a tome on all my hunters, including this one:
http://eu.battle.net/wow/en/character/r ... nga/simple
As you can see, her gear is even worse than yours, and this is after I got a few pieces of loot, my ilvl was something like 420 when I did the dinomancers. It was most painful on her, because I had to heal my pet a lot while doing it, and if I pulled two dinomancers, it would sometimes end with my pet dead (I was using a parrot to tank, so a better pet like a beetle or turtle would probably not have the same problem in equal degrees). So, I waited for them to respawn and pulled one at a time. I seemed to have more problems getting my silencing shots off on time, but that's probably because they had time to heal more often than with my better geared hunters. I would advise just using some cheap focus skills while waiting for the first heal, as soon as it comes, silencing shot it, and then start using all your CDs, to try and burn him to the direhorn stage as fast as possible. Once he's a direhorn, you're all good, and can take your sweet time about killing him, as he won't heal any longer.
Also, if you do pull two, just concentrate on keeping your pet alive and focus on one, as they don't heal each other, only themselves.
Edit: I can't remember if I was Survival or BM on her at the time, but Peanut's response makes me think that I was probably Survival as I had real problems keeping my pet alive. This hunter used to be Survival only, but I specced her to BM for the pets, after deleting half of my hunters, I just don't remember when I did it.
Good luck!