If you don’t have NODO this hack worked for me:
1. Start Zune
2. Turn off the Data connection and Wifi on the Phone
3. Connect the Phone with the PC (USB)
4. Start the update search in Zune
5. About 3 seconds later, disconnect your PC from the internet (Turn WLAN off).
6. Zune finds NoDo-Update. Press OK.
7. Connect to the internet again and install the update!
Thanks to www.wpcentral.com