You can use fastloader to back up your games into iso format. Daxiso creates .dax files which is compressed version of an iso. They will only run on the daxiso launcher. For some newer games that require updates, you may have to use devhook to launch the games and i believe devhook only runs iso files, but i am not certain about that. Also, you can only run backups on psp with version 1.5. Hope I was helpful.