viragom

I think it's hard to say whether he is "part cat", or whether his mutant ability just resembles that of a cat (healing factor aside), PARTICULARLY if you take into account the Wolverine: Evolution arc (which just confuses matters even more). I think the fact that Sasquatch was lumped in with the mutants that are supposedly descended from wolves indicates that not a lot of thought went into that theory, and hopefully we can disregard it... So yes, Sabretooth has claws, heightened senses, sharp teeth and is very agile like a cat, or a sabretooth tiger like his namesake, but he's not neccessarily somehow descended from one, considering he's a mutant. 
There's plenty of comics dealing with what happened once Creed's powers started to manifest and as far as I know there's nothing strange going on (like in the old Wolverine comics where Logan was actually raised by wolverines...) to imply that his cat-like features are anything more then a mutation.