International student living in Taiwan applies for visa to HK

Hello! I'm a Vietnamese passport holder, will be doing my exchange semester in Taiwan next month. I wonder if it is easy to apply for a tourist visa from Taiwan to HK when I am there in Taipei. FYI, I'm also holding RP of Belgium (my original university is in Belgium) Can you give me some advice on what to prepare in advance and some website to check on the procedures?
Thanks a lot!