osTicket doesn't really have a user account system in the traidiaional sense. User access is based on email+ticket ID, so in effect each user can have multiple working login combinations and there is no centeralized user account.
To incorporate one involves greatly changing a lot of the osTicket code to the point that I'd say that if you're not intimately familiar with the osTicket codebase, you might want to consider (professional support) for that undertaking.
That said, user accounts are, I believe, planned for a future version of the script.
Alternately, for a slightly less polished, but much easier to accomplish solution, you could put osTicket behind a restricted user area and simply access the session data to grab the email and use it to auto-populate the ticket forms, then modify the script to fetch tickets based solely on email and not email+ticket ID.
