Note that if you have any previous v3.00 build already installed, you only need to copy UPDATE.ROM to the /POWERPAK folder on your CF card, start up your PowerPak, go to the settings menu, and select "Check for firmware update." After the upgrade flashing procedure has finished (i.e., the PowerPak intro screen appears), power-cycle your SNES just to be sure, and you're all set.
On a side note, the source code is available on GitHub as well, so if you should encounter any potential bugs, feel free to open an issue there, and I'll look into it ASAP.
As with the previous releases, just copy the contents of the "POWERPAK" directory from the archive root onto your CF card, power on your SNES, and you'll be prompted to update. Make sure that you have v2.00 (non-beta) or v2.01 already installed if you want to do an easy upgrade using the in-system flasher. In case you need any of the previous versions, grab it from the SNES PowerPak firmware page.