PGEN can be placed on a memory card and be loaded via Macrus R Brown's exploit. Without going into much detail, this will allow you to use PGEN on a completely un-modified PS2 without the need for a swap trick or similar. In order to load PGEN via this exploit, you must prepare a special save on your memory card (which will show up in the browser screen as "Your System Configuration"). You can use PGEN as your BOOT.ELF. For more information on setting up this exploit, please see 0xd6.org. PGEN will allow you to load rom files stored anywhere on your memory card. It is recommended that you place your roms in the same directory as the PGEN elf file, as when a memory card is selected from the PGEN romlist it will default to the directory on the memory card where the exploit data is stored (usually BEDATA-SYSTEM or similar).