Yes it is possible.. Just add a new form box to your registration form that writes the data it includes to fieldx in userprofile field. I'm sure both you and Arunan can handle such a small hack without my help..

( I recall I give this hack recently in General Hacking Discussions forum either?)
However I dont know how you envision to check the validity of the username, new member entered. What if a user claims that he is "Logician" when he is registering? It's not hard for anyone to find usernames of vb.org, neither have you a method to check his word's validity..You can not also know if the vb.org username is a valid vb licence owner either. Everybody can open an account here..