Actually, a Hong Kong visa can be applied from Hong Kong Immigration
Department by POST directly, even there's no Chinese embassy in your
city, or there's something trouble with Chinese embassy.
Please refer
http://www.immd.gov.hk/ehtml/id1004.htm
You may print out the PDF application form, fill it and attach
necessary document such as passport COPIES, mail to Hong Kong directly.
Note:
1. Email address is very important because HK immigration will contact
you by this way.
2. As now, I only know payment should be made by HK Cheque in HKD, or
let someone else in HK go to the counter to pay for you. (It is better
to ask someone in HK to help you)
3. The process time is much longer than an embassy, it usually takes 4-6
weeks.
4. Fee HK$160(approximately US$20).
5. The visa is a small seal paper, give you directly, and you have to
paste to your travel document by yourself.
In addition, since the visa process of Chinese embassy is sometimes
"terrible", I would like to recommend Wikimania Hong Kong to help with
visa application, not the "invitation letter", but to collect the
documents, submit to the local Hong Kong Immigration counter in Wan Chai
collectively, receive the visa and send to applicants before the
conference. That may be the most convenience.