Sorry mate, can't talk from experience, but:
I know a guy based in HK, living in his home country, who commutes. From what I know, if you are based in HK, you get all the benefits that go with that. This guy does get housing allowance (for a HK apartment), and I think even gets the schooling allowance (in his homeland)....
Once again, heard from a friend through a friend, but thought I'd post as you've received no replies....
edit: I'm not in Cathay, so take it for what it's worth....