There's no way you could employ him.
Obviously if he has suitable qualifications then he could try to get a job (as a language teacher or whatever) in his own right for which he could get an Employment Visa.
If he holds a British passport and you are only planning to be in HK for 1-2 years then he might well get away with simple Visitor's visas of 6 months at a time. for 2 or 3 renewals, but obviously this is not guaranteed.
If, by chance, he holds an Irish Australian or New Zealand passport then he could come for one year on a Working Holiday Visa.
Otherwise there have been reports of "civil union" type couples being granted extended visitors visas for the non-working half. This wouldn't allow him to work but it would allow him to stay here legally. It's going to be a slower process and probably requiring more evidence than a simple dependant, bt it might be doable. VisaPro-Prompt & Professional have a "no win, no fee" visa service so you might want to talk to them to see if they would be interested in taking your case on.