did you try ?http://username:password@www.example.com/
<http://username:password@www.example.com/anyfolder/>


You have two things:
- the <http://user:pass@url> scheme for basic authentication 
(that is, pages that display a message box in the middle of 
the screen asking for username and password)
- "add url"/"capture url" in httrack to handle form-based 
authentication (that is, pages with "submit" button)