Here you go -
http://forum.xda-developers.com/showpost.php?p=12473375&postcount=83
After you get your device unlocked, just use the application deployment tool from the dev kit (It has a menu item in your start menu) and point it to the xap file you can download from the link above (Rafael's post)
Then open it up on your device.
It should be defaulted to hklm\system\platform\DeviceTargetingInfo\MobileOperator
Leave the radio button next to STRING selected and hit the Read button
The second box should read Get String: ATT-US if you haven't modified it.
Put the cursor in that box and hit back/delete until the box is empty.
Type in 000-88 and then hit the write button.
After you do that, hit the read button again - It should now display Get String: 000-88
If it does, exit the app and reboot your phone.
Connect it to Zune and you should receive the pre-NoDo update.
After that, connect it again and see if it finds NoDo.. if it doesn't try the VPN stuff and the counting/data connection disable, etc.