can i change my student visa to a Z visa in Hong Kong?

Please, I am a Ghanaian who just completed MSc in China. currently, I am in China. I have had a job offer. instead of coming to my homeland I prefer to apply for a Z entry permit in Hong Kong. firstly, do I need a Hong Kong entry permit before I can travel there? secondly, what documents do I need to apply for the Hong Kong visa (thus if needed)?
moreover, since I apply for the Z in Hong Kong what other documents would I need to for full this? Kindly tell me the best ideal way. Thank you