Use Free DVD Boot (burned to a DVD-R) or a pre-modded memory card to launch the FMCB Installer through uLaunchELF .
Create a folder named DVD on your USB drive and place your ISO games there. Mcboot Download Usb
Note: PS2 USB ports are USB 1.1, which causes slow loading times and potential stuttering in video cutscenes. If you'd like, I can: Use Free DVD Boot (burned to a DVD-R)
Help you find a (no download needed)
Open the Open PS2 Loader (OPL) app from the Free McBoot menu to launch your games. Mcboot Download Usb
Follow the on-screen instructions to install Free McBoot onto your PS2 memory card. Playing Games from USB:
Extract the Free McBoot files and copy them to the root of your USB drive.