Adding a filter hook to DW Question & Answer ask form for tag input field

Would you like to add a filter hook to DW Question & Answer ask form for tag input field?
I want to change the question tag input field to select field,but I found that there is no API to meet my need,so I have to do like:
http://suoling.net/adding-a-filter-hook-to-dw-question-answer-ask-form-for-tag-input-field/
Best wishes!