Whether you consider it the first, second or third step — it’s a step in the direction of PS3 custom firmware
: JaicraB’s USB Firm Loader. Load [customized] PS3 firmware files off a USB stick in a few simple steps:

1. Download PS3 FTP Server. Install it. Connect.
2. Download and copy the entire “dev_flash” folder to your USB mass storage devices’ root directory.
3. Copy JaiC_USB_FIRM_LOADER.pkg to the root too.
4. Install USB Firm Loader.
5. Now run USB Firm Loader with the USB mass storage device attached; it should return you to the XMB with the firmware loaded off the USB stick.

PS3 USB Firmware Loader

This’ll be used for loading modified RCOs, plugins / modules, etc. USB Firm Loader v0.2 is an early release, so bugs are likely to exist. You will also need PSGroove with peek & poke sys-calls. Our compiled binaries for select AVR USB boards should work.

source - ps3-hacks
source - ps3-hacks via jaicrab’s blog