pseudo-Joomla username suggestion

Thank you for JFBConnect, it is really an excellent extension. You've created something that has so many integration points with Facebook it should really help websites 'go viral'.

I am hoping to use the pseudo-Joomla user option because it makes registering on my site so easy. I wonder though about a compromise option between pseudo-user and full-user (which asks for username, email, password, verify password). What about an option that let's the user specify his username only. This I have seen on a vBulletin FB plugin. I think filling in one field is much less of a hurdle for users than 4 fields, and that way they can choose something more attractive than 'fb_123456789'. And maybe that field could be pre-filled with facebookfirstname_facebooklastname_## where the '##' would be utilized only if there was already a user with an identical username.

Another possibility and probably easier to implement would be to modify the pseudo-user username assignment to be facebookfirstname_facebooklastname_last-4-digits-of-facebook-id. I think the chances of username duplication in this scenario would be small enough to be practical.

Is there a code cut & paste that could accomplish this second option?