To generate a firmware, run (paths may differ):

$ make
$ ./fwdecrypt R0.ROM <optional: destination path>
$ sudo ./patch-firmware.sh files . # needs sudo
$ ./fwcrypt R0.ROM <optional: source path>

After that, R0.ROM is patched and can load Rockbox.

rockbox.sh is a script to put into rockbox.zip. It's a small loader script
that sets stuff up.

files/lib/modules/si4709.ko is a replacement kernel module for fm radio support,
its source code is packaged in ./si4709.7z.