[xwiki-users] User Display Names in Acces Rights Table

Hi everybody, I'm using LDAP for login into XWiki (MS AD), it works very well. But there's something I'll need to change: when a user is editing some page's access rights, when he/she selects the "User" radio button, the list that appears is based on the user's objetc names (that came from the sAMAccountName LDAP field). Since our login field (and the username) is the registering number on our company, the user's list on the access rights appears as a bunch of numbers, and not the users' names, what makes it difficult to the author guess which one is to be granted the desired right. I would like that the "first_name" field (or another one from the user's object, mapped from LDAP) is shown on this list. I've been looking around the rightsUI.vm and usersandgroups.js, but could not figure out how to do this. I'm using XE 3.0RC1. Any ideas? Regards, Ramon Gomes Brandão