[I]this guide is orginally posted by Krack3n
You'll need these two programs.
• PS2 Save Builder
• PS2 save converter
• First find a save you want to convert. I'll pick the first one which is in .cbs format.(CodeBreaker)
• Now we will open the .cbs save we downloaded in step one, open with PS2 Save builder and Save as a .xps format PS2 save.
• Now we will open the .xps file with PS2 Save File Converter and Save as a .psu format file.
• There you have it, now your save is converted to .psu.