You need 5 documents:
- Invitation letter from the chinese administration to the Chinese Consulate in Hong Kong
- Company licence
- Company letter that states that you work in the company and what position (the best is to state in the letter that you work as a consultant or in the Management team).
- Working permit delivered by the Chinese authorities
- Health certificate: medical exam done in China
I went to some great agency. They take care of everything for you : forever bright Hong Kong.
Most foreigners use their services.