You'll find that very few airlines on the mainland are hiring expat FO's due to an ever increasing number of their own cadets.

Hong Kong Airlines and Hong Kong Express both however do hire expat FO's, as does Air Hong Kong (yes, a different airline), a cargo operator flying A300's and B744's. Their hiring page for FO's is;

Air HongKong

I'm not sure about the former, but all of my mates who have flown for Hong Kong Express, and there are a few, showed up on their doorstep. I would garner that the same would ring true for Air Hong Kong Cargo.

China Cargo does have some expat FO's on the B744 out of Shanghai (used to be Great Wall) but I do not know if they need more. I'll try to find out.

Also, of course, SQ Cargo. In my opinion an excellent company to work for. Here is their FO hiring page;

Welcome to SIA Cargo - Career

Good luck with it.