Dumping firmware
The first step to examining iPod's firmware is getting an image of it.
---Under Linux--- Getting a firmware dump is very easy in Linux. Just:
Make sure the iPod is plugged in. Type "dd if=/dev/sdX1 of=dump.img" in the terminal, but make sure you edit the drive to match your configuration. A dump.img file should be created after a while. If you have a lot of data on your iPod, it can take a very long time.
---Under Windows---