[Flow] Login with Facebook additional to classic Registration/Login

[Patric Eckhart]

Hey guys,

on my website I have a classical Registration/Login Process.
Users sign up with their username, email and password and sign in with username and password.

I would also like offer a login with facebook. Is there any documentation or source?
Has someone already realized it with Flow?

In my fluid templates I use many <f:security.ifAuthenticated> and <f:security.ifHasRole role="Visitor">