BELARUS CITIZEN PROCESSING CHINA Z VISA IN HONGKONG

HELLO!

I am a Belarus citizen currently staying in Nanning, Guang xi, on an a one month L visa - and have been offered a job here which i wish to take. In order to process the resident Z I need to go (back to - I arrived via with a one day transit G) to Hong Kong. Please can you tell me what I will need, the process for applying for it within mainland china, and specifically - if there is such an office - from Nanning?

Many thanks in advance

Anna