Things You'll Need
Instructions
Connect the PSP to your computer using a USB cable. With the PSP turned on, go to the Home menu. Scroll down and enable "USB Mode." Insert the SD card.
Download Popsloader. Using Winrar, extract the contents of Popsloader to your PSP's SD card.
Download PSARDumper. This program will extract the data from the firmware update. Using Winrar, extract the content of PSARDumper and copy the "newspsardumper" folder to the "PSP/GAME" directory on the SD card.
Download the firmware update that goes with the version of Popsloader you want to download (a link to a list of firmware is available below). Once downloaded, rename the file to "EBOOT.PBP." Copy it to the PSP's SD card.
Use the PSP to navigate to the game menu. Doing this will disconnect USB mode. Launch PSARDumper from there. Press the square button to start decrypting firmware files. This might take a while.
Place the PSP back into USB mode. Find the "F0 folder" on the SD card. Copy the following files to the "seplugins/popsloader folder" on the SD card: "3.00-3.03: kd/popsman.prx, kd/meaudio.prx, kd/pops.prx, vsh/module/pafmini.prx", "3.10-3.30: kd/popsman.prx, kd/pops.prx, vsh/module/pafmini.prx", and "3.40-3.72: kd/popsman.prx, kd/pops.prx, vsh/module/pafmini.prx, vsh/module/libpspvmc.prx."
Turn off the PSP. Turn it back on while holding the R button. This will put the PSP into "Recovery Mode."
Go to the Plugins menu. Enable popsloader.prx. Exit Recovery Mode. You will now be able to play PS1 games directly off your SD card in ISO or BIN format using Popsloader.