Allow Facebook login

We have public machines set up with our website only, but we want to implement a Facebook login. For the FB login we need to redirect to https://www.facebook.com/login.php.
The software is working fine. There are two Admin accounts, one with IE: Secure lockdown and another Admin. I don't know how to allow the Facebook login page (only the login page besides our domain) in the first one. How can I do that?
Thanks in advance.

You will just need to add the appropriate Facebook URLs to the Alowed Sites list in the Secure Lockdown settings.