Change Name field for users to login with

The previous IT person that set up our RT instance decided to use the CN (Common Name) Field for logins, this requires users to put in their full FirstName LastName and doesn’t conform to the shortname format we use elsewhere, jsmith, for example.

I can easily change the name of a single user in the RT web UI and then update the LDAP/AD section to use sAMAccountName, the issue is updating the record for all users.

I looked in the mysql database at the Users table, the field to update is Name. Is there a good method for updating all rows with the proper shortname of the users? Or is there a better method such as having RT query AD to update the Name field with the chosen AD attribute?

Any help would be appreciated