It seems that it isn’t possible to set the DVD region code in mass on newly deployed mac hardware. What you can do however is change an authorization file to allow unprivileged users to set the region code initially. (Changing the region code after the initial setting is another matter and will continue to require admin privs)

To allow non-privileged user accounts to set the region code initially edit:
/etc/authorization

Look for “DVD” and edit that section so that it reads “allow”
(you can edit a copy of this file with textedit or with a plist editor, then copy the new version into place …)

Here is a sample of what you are looking to do …

    <key>system.device.dvd.setregion.initial</key>
<dict>
<key>class</key>
<string>allow</string>
<key>comment</key>
<string>Used by the DVD player to set the region code the first time.  Note that changing the region code after it has been set requires a different right (system.device.dvd.setregion.change).</string>
<key>group</key>
<string>admin</string>
<key>shared</key>
<true/>
</dict>