156w ago - Since the release of PSGrade there have been lots of PS3 Downgrade Hex Codes for all types of devices, and today Matrix15 and xXJohannXx of Logic-Sunrise.com (linked above) have posted a PIC18F hex code and guide which can be found below.
To quote, roughly translated: After leaving the downgrade for the different clones based Atmel microcontroller, the service mode is finally available to the dongle-based ICP such as ZBN SPI USB V1, V1.1, V2 , or PS3liberator NbzgroovePIC v1.0 at PICDEM bootloader is available.
The downgrade process is similar to any other dongles, you'll need: downgrade-files (http://www.logic-sunrise.com/telecharger-172586-downgrader-files.html)
1 - Upgrade your NbzgroovePIC or module ZBN with the update for the downgrade. (The update is done the same way that a jailbreak for maj.)