JFBConnect doesn't support this, and not sure how useful/streamlined it would work out to be to implement. To get the user's profile data, they have to authenticate through Facebook using a button on your site and then grant your website access to their profile data. This could be done without creating them an account on your site, but JFBConnect is designed to automatically create them an account once they go through this process.
You could do this all silently, where an account is created, but the user doesn't get an email or even realize the account was created. At that point, the tools in JFBConnect could be used to fetch any of the available Facebook profile data you're looking to get.
Of course, Facebook has been in the news considerably lately for sites that have taken too much data about users. All apps have to go through an approval process now to explain what data they want from users, why and what they will do with that data. If you're just looking to harvest user info, you could run into approval issues.
I hope that helps, but of course we can help with anything you need.
Thanks,
Alex