Mexican prolong china visa in HK

Hi, I'm mexican, I came to mainland china with a one-off entry visa. I what to prolong and have a multiple entries because I need to go HK for work. Do you know if I can do all the process to obtain that kind of visa if I go to Hong Kong? I know that this is not longer possible for french citizen...I just want to make sure that the possibility exist for mexicans. Thanks in advance.