I would like to follow up on this request too.
I have just downloaded the tar.gz of the final release of Openacs 5.0 and I am studying the authentication parts.
It seems that you can define several "authentication sources" or authorities. Looks good if you need a totally different registration process/page. However, what if you would like to stick to the current registratio process but just add one or two attributes like student ID as mentioned above ? What would be the best approach ?