External login

Is there any way I can authenticate a user (I will be using LDAP, and I can make that work INSIDE Xataface, but that's not what I need!) before redirecting to a Xataface application page, so that the Xataface app can pick up the user id (through a cookie or session variable, perhaps?) and then apply the appropriate permission to that user's access? I'm trying to build a system around Xataface and a couple of other products, and I'd like to set up something like SSO for the intergrated whole.
Thanke for any help that anyone can provide.
Kevin
Thanke for any help that anyone can provide.
Kevin