Create script that using a user's Facebook username and password is able to do a facebook login to a site like HomeRun.com. At that point a the same script should be able do a web request and scrape data from the [url removed, login to view] user's account. If you are familiar with the term "session hijacking" than you may have the skill set to complete this project. Fear not about the legitimacy of this project, this is completely user sanctioned activity - our service already does this with standard usernames and passwords, we additionally want to do this with facebook logins as well since this is starting to become more popular as a login mechanism. oauth is not an option at this point since enough of the sites we are interested in have oauth as an option.
This also assumes that the Facebook login uses the Facebook open graph api.