How do you have users fill out a survey (form) without having access to the Application itself?

How do you have users fill out a survey (form) without having access to the Application itself?

I have a number of consultants who visit a site and need to fill out a site assessment created in Creator. I want them to have unique login and passwords and NOT to have access to anything else but the form they are required to fill out (via permalink?). The main issue is that it seems that access to the form via permalink requires them to sign in using the same login as the administrator which could easily give access to the application, not only the form they are required to fill out. Any suggestions?