Now that I look at the database I see how there's a "XenForo_Authentication_vBulletin" Where can I modify this? Edit: Nevermind, I found it. There's a folder called Authentication, go figure. Now I see I can create my own authentication scheme easily by modifying an existing one. The problem would be setting them per user. A temporary fix for those importing from another software using vBulletin as an intermediate would be to modify vBulletin.php directly. I don't think there is an AdminCP option to do this. I assume this is planned but not in the beta?