1. Make sure your phone is rooted!
2. Connect it to the computer in USB debugging mode (charging only) / make sure all the drivers are properly installed
3. Extract "LG Optimus G underlying backup tool" and run the .bat file inside, after a successful backup you'll have 5 more files in the same folder. If so, you're good to move forward. (Please note that you might need to grant ROOT permissions on your phone once you run the .bat file
4. Extract the EDGE file to the LG Optimus G underlying writing tool folder and then run the .bat file.
5. Reboot, enjoy edge.