Can I apply the Hong kong transit visa in China embassy in New Delhi?

Dear Sir, I am from Vietnam ( Vietnamese citizen and passport) and I am going to India for tourist from December to February. After finishing the India trip, I am planning to visit Hong kong when I have one-day transit there. does it still take 4 working days to deal with my application? Do I need to apply financial standing, employment, tourism itinerary and accommodation arrangement even if I just want transit one- single entry?
Regards