You can use the hidden MFG app (available on every LG phone) on your quantum to change a registry edit and unbrand your phone to get 7740 and then 8107. I did this with my optimus 7 and it was simple enough.
Originally Posted by shoe7400
In case this is something you'll be interested in doing here's the instructions:
1. Dial ##634# on the phone, it should make the MFG app appear
2. Enter 277634#*# as the password
3. Go to Engineer Menu -> Other Settings -> Edit Registry
4. Select ROOT_PATH: HKEY_LOCAL_MACHINE
5. Input SUB_PATH: \System\Platform\DeviceTargetingInfo\
6. Input KEY: MobileOperator
7. Select Data Type: STRING
Now hit query, this should show you ATT-US (I think) which is the branding of the phone. Save that key in case you want to brand the phone again.
Next, you can replace that with 000-88 which is the unbrand key and tap set. This should change the key. You can double check by tapping query and confirming 000-88 appears.
Finally, all you need to do is connect your phone to zune and check for updates, you should have both 7740 and 8107 pending.
Hope this helped you :)