Dear Amy,
Greetings from Janet, Top China Travel.
Thanks for your message. Regarding your question for the visa application, if it's possible to get it in another country but not China, I think it's not, you need to apply for the visa in your country, you can't get it in another country. And Hongkong is not a country. :)
Have you plan for your China trip? Do you need my help to design an itinerary for you?
Should you have any additional questions, please feel free to contact us.
Best Regards