If you want my advice-- and no one does-- I'd say just expand the the vampiric template to giants, and that'll give you trolls and ogres as well as, well, giants. It seems to me like this very issue was covered in some capacity over at the Wizards site on Elite Opponents or Fight Club. But that's either just sticking the vamp template on a demon even though its the wrong type, or making a half-vampiric tauric elf manticore, which is just wacky-sounding. If they had a cool, simple name like, I don't know, Slirges, it wouldn't be so bad, but the whole template-piling-on ends up sounding like some wonky version of a bad D&D political-correctness satire: I'm a half-vampire-tauric-elf-manticore-American type thing. Which, granted, would be virtually assured a spot on the local news team, but that's not what we're debating right now.
There are some templates that might help you, though. Half-troll was mentioned as a way to make a troll (part) humanoid. If I am misremembering that, I apologize, but its from a book I don't own. (Fiend Folio maybe?)