Things You'll Need
Instructions
Insert the MMS into the PSP Slim's memory stick reader.
Insert the Pandora battery into the PSP Slim's battery compartment. Turn the PSP Slim on.
Press the "X" button to install custom firmware onto the PSP Slim.
Press the "X" button again to shutdown the PSP Slim.
Reinsert the normal battery into the PSP Slim and turn it on. It will now be running custom firmware.