I wrote this originally as a guide for my own website with my experience and risky flashing method for the BIOS, but I’ll just copy and paste the actual guide to Tech Jawa as well.

You can read the source article here!

1. You’re going to need to disassemble your CR-48 device. THIS STEP CANNOT BE SKIPPED. There is a small metal strip inside the case that touches a sensor on the motherboard of the unit. This protects against the BIOS being written over. To do this you want to remove all the screws on the case (circled in the image below). You’ll need a very tiny screwdriver for the small black screws, be careful not to strip them like I did or you may never get the casing off. You also have to remove the back two rubber feet (they’ll stick back on without issue don’t worry!) and remove the screws underneath as well. Once the screws are removed, start removing from the monitor hinges pulling upward carefully, work your way around to the side OPPOSITE of the power input, that side will come off very cleanly and allow you to avoid any breakage on the side with the input ports.
2. After you have the case removed, go ahead and flick the developer switch ON as shown below. Set the netbook on a smooth surface (since it doesn’t have it’s bottom, make sure its nothing metal) and plug the device in and turn it on. The CR-48 should tell you that the verification of Chrome OS is turned off, let it sit at this screen for a moment and it will eventually start “erasing the stateful partition”. Let the process complete and reboot. Upon reboot you’ll be at the Chrome OS setup screen as if it was out of a new box. You’ll want to at least get as far as when it lets you select your WiFi network. Be sure you’re connected to the network before continuing!
3. After you’re on WiFi, press Ctrl+Alt+Forward to drop to a shell.
4. Enter the username as chronos with no password required.
5. Now that you are logged into the shell, we need to download the BIOS file. issue the following command. wget http://www.techjawa.com/cr48bios.bin
6. It’s up to you to backup your current BIOS, you can do this by the issuing the following command. sudo flashrom -r backup.bin
7. It’s also up to you to BACK UP THAT FILE! Do something, copy it to your flash drive, boot into the CR-48 developer mode and email it to yourself or something. You’ll figure it out if you want it badly enough.
8. After you’ve taken care of that, or not if you don’t care about restoring it, we need to flash the new BIOS. Just issue this command. sudo flashrom -w cr48bios.bin
9. Wait for the process to complete, reboot, and that’s it. Now follow whatever guide you’d like for your specific operating system, and remember if you’re installing Windows 7, reset the BIOS to optimized defaults!
10. Enjoy! And don’t forget to replace the cover and attach all the screws again!