Non-LDAP user directory, uid change

Hi,

due to a special LDAP layout and some other requirements our company needs to use "Non-LDAP user registry" = UNSUPPORTED user registry type.
We use Tomcat and have our own Realm which takes care of authentication and group mapping.

The (very big) problem is that even non-admin (JazzUsers) users can change their userId (and email and name -- which is a minor problem compared with userId...).
Is there a way to disable this? For example to make it read only as in the case of Tomcat or LDAP? (LDAP is the best as the the user cannot even edit the Name nad Email).

Thanks for any replies in advance.