Canadian passport applying for Chinese visa from Cambodia

Hello, we are a family of 5 (2 adults, 3 children) travelling for a year and we will be in Cambodia in September. We wish to make an application for entering China from the embassy in Phnom Penh. We already have our flights back to Canada booked from Hong Kong. We will be travelling around China for 3 weeks entering via train from Vietnam. Is it possible to complete the application in Cambodia?