How to register “Custom Ask” page/function?

Hi,
I have done some customization in “function ap_ask_form()” or in  “function ask_from_content_field()” to be more specific.
But I want to keep your function / Ask page as its, and keep the changes in function “custom_ap_ask_form()”. So, far I have got partial success.
My question is –
What should I do so that it can detect “custom_ask” in the url, like yours is “localhost/wp/question/ask/”
Hope you understood what I mean?
Thanks
Regards