To add  information to the custom  column you add you need to edit the item
just like you would in any other SharePoint list. Click on the person or
group and then choose Edit Item from the toolbar. You will see the
additional columns  and can add information. Profile synchronization can
pull information from active  directory to be added to a user's profile in
MOSS, but that information has nothing to do with what shows up in the
People and Groups list. You would need custom code to populate  the
information in any way other than manually editing each person or group in
the listview.