The only GA in Hong Kong is the Hong Kong Flying Club. They only operate fixed wing from the airfield at Sek Kong, and then only when the PLA will let them. It's very expensive as AVGAS isn't available and has to be imorted by the Club from Singapore. There's also some rotary during the week from the old airport at Kai Tak.
http://www.hkaviationclub.com.hk/nav16.html
One alternative is to book a 737 sim with Flight Experience at the Megabox mall in Kowloon. You can have a go at the IGS approach at the old Kai Tak. See
Flight Experience Hong Kong - Home Page