Things You'll Need
Instructions
Download PSP ISO Compressor. Install the program by double clicking it after it finishes downloading.
Open PSP ISO Compressor on your computer and select "Compress ISO ->CSO" from the left side of the window that appears.
Click the "Input File" button and select your ISO file that is on your computer and click "OK." Click the "Output File" button and select a place to save the new CSO file. Click "OK."
Click "Compress" to convert and compress the ISO into a CSO file.