Well, I just looked it up and Hua Hin's IATA code is HHQ instead of HUA. I would suggest, for not so famous airports, using the full names instead of abbreviations would be a better idea.

For your question, Hua Hin is neither a scheduled destination of CX nor KA. I don't know if there are chartered FLTs that goes to Hua Hin, but you can only book normal FLTs on CX's and KA's websites.