it seems that you want to use one save for a different psn id. the firmware does not matter, however you may be able to use the save by copying all the files except the param.sfo file. for example, say you want to use a Red Faction save that someone has posted online on your main account. first you need to make a save file on your main account and then copy it to usb. simply open the folder that is for the save file on your pc and open the folder of the savefile that you want to use, copy and replace every single file from the save you want to use except the param.sfo file onto your original gamesave. make sure you backup your original gamesave prior to doing this though as it doesn't always work. also, when diconnecting the usb drive from your pc, make sure you go to the drive in "my computer", right click and select eject. Like I said though, this doesn't work for every game but it's worth a shot.