To figure out how to compile the Linux rootfs/kernel for this project follow the Linux portions of the "Firmware Guide" and the firmware parts of the "User Guide".

A quick guide to do most of what you want is below:

A new version of the current SD card can be created simply by creating a 1GB FAT32 "OS" partition at the start of the SD card and a 1-3GB FAT32 "DATA" partition over the rest.

The current configuration expects an "init.sh" script in the DATA partition of the SD Card. This script is run after the DATA partition is mounted. This is to allow for quick changes to the OS without needing to recreate the rootfs.