This post / method is now outdated – It is now easier and quicker than ever to update directly to 6.60 CFW. I’ll leave this post online for those that want to do it this way of just need the information
Click here for the new guide / updated method
First you’ll need to install / update to 6.20 official Sony firmware, to do this download the official firmware below and extract the UPDATE folder and contents to the PSP/GAME folder on your PSP.
Go to the memory card on the PSP and run the update.
To apply the custom 6.20 TN firmware and prometheus ISO loader copy both folders and contents from the download below to your PSP/GAME folder on your PSP.
Go to your memory stick under the PSP menu and run TN-HEN first, then you will be able to launch the ISO loader and play your backed up ISO / CSO games!
Official 6.20 psp-6-20
Custom 6.20 TN + Prometheus ISO Loader custom-6.20
