Mattd
Basically it doesnt matter how long you have been with your partner, defacto relationships are not recognised in Hong Kong.
If your partner is under 30 and Australian ( maybe other nationalities also, but not sure ) she can get a 12 month work visa.
If your partner has a required skill here she could easily get a work visa ( ie teacher ) and I think even some english teachers ( which is what a lot of expat wives do ) can get visas, but I think this is rare.
There are plenty of shonky mobs that will hire your partner and pay her cash, of course if she gets caught you could both get ejected from HK, which might be a bit of a problem for you
Otherwise ( depending on your passport ) your partner will have to leave HK every 3 months.
Everything will have to be in your name, and if/when you have an issue with any utilitys etc, they will only speak to you, a bit of a problem if you are in NY when ( not if ) the TV/Phone/Internet goes tits up.
Cheers