I'm trying to implement a quasi-bridged system between a vBulletin and WordPress installation, and I want to use OpenID as the backbone of this bridge. The goal is to be able to share user databases without literally doing so - it's much simpler, safer, and easier than physically combining databases.
However, as I wish for accounts to be centralized on the Forums, where all of our users are registered, I need to disable normal registration. Is there a way to ONLY enable OpenID login and registration, and turn of WordPress's default user/pass system? I want it gone with the wind - never to return.
In addition, I'm wondering if there's a way to code an OpenID login widget after normal login has been disabled. Ideally the whole registration form (consisting of simply the OpenID text field and login button) would convert to a neat little profile summary after the user has logged in, saying "Welcome, <username>!" and possibly showing a Gravatar or something, and a link to their profile.
All the help I can get is appreciated. Thanks! :)