PSX-On-PSP Game Save Solution For PSP
I tried it out and figured out how to make sure you don't overwrite the same gamesave files. I've even included a hexeditor just incase you don't already have one. Again I would like to Dark_AleX for making this all possible! All it took is 1 small hex edit.
1. I tried this out using Raiden Project and it worked with no problem. First of all go ahead and convert your psx for use on the psp.
2. After its done open up the new EBOOT.PBP file in the hex editor.
3. Search for 94476. You may have to skip over a few finds. In the hexeditor below the part you edit shows up as _SCUS_94476. Just overwrite the numbers with any numbers you like but use the same about of characters. I pretty sure you can use letters as well but didn't try it.
4. Save the file and transfer to your PSP. 
That's It. Now you don't have to worry about overwritting your saves.