Hong Kong Transit Visa

Hello! I need some information regarding Hong Kong Transit Visa. I am a Sri Lankan Citizen with a Canadian Permanent Residency. I am currently living in Canada and is planning to visit Sri Lanka in next month. On my return trip I have a 2 and 1/2 hour transit in Hong Kong and I was wondering if you would be able to tell me if I can come to Sri Lanka and apply for the Transit Visa at the Sri Lankan Chinese visa consulate office? If so how long is the process and if it is possible to get the application expedited? Please advice! Thank you so much!