Works like a charm! ThanksEasiest way to get this to work is how VanillaXpC tried to explain it. Basically you want to create an offline profile, use it's ID #'s to duplicate your main accounts save for it (making the offline account the same level as your main account), and use the GPD on the offline account. I suck at tutorials but I'll try.
USE HORIZON FOR THIS!
1. Disconnect from your wireless or wired connection.
2. Create an offline profile/account (this will be the account you will be injecting the GPD into)
3. Load up Borderlands 2 at Sanctuary with your main account and offline profile.
4. Save and quit so your game is saved (and so you're at Sanctuary by the gold loot box, if you have the premier club dlc this will also give your offline profile 1 gold key)
5. If using a flash drive, copy (do not move) both the offline profile and your MAIN ACCOUNT'S gamesave to it. Otherwise, just drag them to your desktop to edit or edit them within Horizon.
6. Get the IDs for the offline profile and copy and paste them into the copy of your main account's save. Rehash and resign. This will make your offline profile have the same rank as your main account.
7. Now replace the GPD in the offline account with the 255 keys GPD. Rehash and resign. Move to harddrive/flash drive.
8. Load the game offline split screen and use your offline profile to open the box but have your main account take the loot.
9. If you don't want to lose the keys you use, just sign the offline profile account out without saving.
Worked perfectly for me. Sorry my tutorial sucks. I'm no good at writing them out. Easier to show/do lol. Make sure you save the game afterward with your main account so you keep the guns and loot lol. Also as you progress and rank up, you will have to reduplicate your main account's save for the offline profile so that you get guns that "fit" your current rank.
This also ensures that your personal badass rank for your main account is NOT AFFECTED! :)