I am building a website that uses facebook connect for users to log in, however, it is for a specific group of people. Is it possible to only allow specific people to log into the system. As in prevent people who arn't on the list from being able to use the app?
Sandbox-mode the app and add everyone you want to whitelist as a developer.
You will have to manually import a list of faecbook user ids and block them manually, or you could leave you application in Sandbox Mode and manually add the users you want as Testers of the application. Bare in mind that when an application is in sandbox mode, there are some limitations such as app invites. App Invites will not be recieved by any user that is not listed in the Testers/Developers/Admins lists of the application.