I'm using this mostly to host files relating to the Cr-48.
You will need to have the BIOS write pads physically isolated on the board. (TODO: add image.)
Once you've done that, toggle the switch to Developer Mode, it's inside the battery bay and hidden by a black sticker.
After that is toggled, your Cr-48 will show a splash screen, just wait, the machine will long beep twice, then load into ChromeOS. (There is another way to skip the splash by a certain key combination, but I don't remember which. I'll add it if I find it again.)
First time the ChromeOS will be wiped switching to developer mode, this will take around 5 minutes, just let it do its thing. Then it will reboot, splash screen, double beep, yada yada.
Once that's done, get to the setup screen and connect to Wi-Fi. Once you've done that press Ctrl+Alt+F2/(Forward button) to drop into a Dev console.
From here, login as chronos, there is no password by default. From there, escalate your privileges by doing sudo su, then backup the original BIOS and flash the InsydeH2O BIOS.
I'd recommend setting up a mount point with a USB drive, I did that by first finding where the USB drive is located with fdisk -l, and then mkdir /tmp/mnt && mount /dev/sdXX /tmp/mnt.
To back up the original BIOS, do flashrom -r <backup name>.bin and copy it somewhere safe (like the previously mounted USB drive). Once that's done, go to the next step.
Then you'd want to download the bios by doing wget https://github.com/hanakomisa/cr48-stuff/raw/main/cr48.bin flash your BIOS by doing flashrom -w cr48.bin
Alternatively, just copy it to the USB drive beforehand and skip the wget step.
Once it's done (ignore any SPI errors), reboot and your Cr-48 should behave like a normal Netbook now. If not, then your flashing process may have went wrong. In this case, you'd likely have to do a physical BIOS flash, it's another can of worms I won't be touching at least right now.
TODO: add this. but a TLDR is get a Linux livecd, install flashrom, then flash the backup BIOS. flashrom -w alone may not work and might require additional arguments, I believe it was INTERNAL something.