Old topic, but I just tried the following out to get JPCSP saves working on a PSP and it actually worked, at least for 1 game so far. Needs a HEN/CFW though. Got my Disgaea: AoD save transferred over successfully.
There's a plugin called Save Game Deemer that outputs decrypted save data to a separate folder when you save, and loads those files, instead of the original, if they're available. It's meant for save game editing, etc. Anyway, I suck at explaining things, but basically you bait and switch the JPCSP save with the decrypted save the plugin outputs and trick it into loading that instead.
Edit: Bleh, I give up. can't can't any other saves I have to transfer over with the above or savestates. Guess not all games work.
There's a plugin called Save Game Deemer that outputs decrypted save data to a separate folder when you save, and loads those files, instead of the original, if they're available. It's meant for save game editing, etc. Anyway, I suck at explaining things, but basically you bait and switch the JPCSP save with the decrypted save the plugin outputs and trick it into loading that instead.
Edit: Bleh, I give up. can't can't any other saves I have to transfer over with the above or savestates. Guess not all games work.