z-visa requirments

Dear Sir or Madam,

My Husband is full time employed at TEFL Academy as an English Teacher, he is holding British Passport and has Hong Kong Identity Card. The school that he he is employed at will issue him Z visa invitation letter. Since he is in China now and he is a Hong Kong residence he will apply his Z visa from Hong Kong. On the other hand Myself (wife) and our children are holding Pakistani passport and we are in Pakistan. What is the procedure for us to have the z visa so we can join him and what are the required documents.

Please note that my husband is in China and holding British passport and we are holding Pakistani passport so how can we accompany him in china as he will apply for Z visa from Hong Kong since he is hong kong residence and how can we apply for z visa to accompany him as we are in Pakistan and holding Pakistani Passport.

Your kind reply will be very much appreciated.
Looking forward to hear from you soon.

Regards

aaliya