* Check that you have an Japan or US version of Phantasy Star Portable (Japan:

ULJM-05309, US: ULUS-10410). Work on the European version will be following soon.
* Extract the contents of the 'MS_ROOT' folder from the ZIP file into the top-level of your memory stick. (HINT: If you wind up with an 'MS_ROOT' folder on the stick, you've done it wrong).
* Start the game, and as soon as it gets to the 'Press START' screen, press START. If you wait until the demo has started, the exploit may not work.
* The screen should go blank, and the exploit will start after a few moments. It doesn't do anything except look pretty at this stage - but feel free to enjoy the first homebrew on your PSP Brite