Dual booting KaOS Linux on a Chromebook is relatively easy as long as your Chromebook uses the SeaBIOS and is setup in developer mode. To accomplish this task I used my HP 14 Chromebook and an external USB Drive.
Download the KaOS Linux iso
If you have not already done so, download the kaosx linux iso.
Create a boot-able USB Drive with KaOS Linux
Note: This step can be accomplished on any device running Linux however; in this case I did this directly on the Chromebook.
Once the Chromebook is in developer mode press CTRL + ALT + T to open the CROSH terminal. Run the shell command. This will enter you into a Linux terminal. You should then run df -h to determine what the path to your USB Drive is. For me it was /dev/sdb. At this point we have already downloaded the ISO image so all we need to do is run the command:
sudo dd if=/path/to/the/downloaded/iso of=/path/to/the/USB/device
(Example: sudo dd if=~/Downloads/KaOS-2014.01-x86_64.iso of=/dev/sdb )
Once the command is complete I recommend running:
sudo umount /path/to/the/USB/device
This took some time from the Chromebook; be patient and wait until it is finished or you may end up with a corrupt USB.
Restart and boot from USB
Ensure the USB Drive is in the USB 2.0 slot. For some reason It does not work in the 2 USB 3.0 Slots.
Reboot the Chromebook and at the Dev mode screen (The first screen that opens on reboot) press CTRL+L (legacy boot mode). This will bring you into the Boot menu. You need to quickly press ESC before it auto loads the primary drive. This will allow you to choose your boot device. From here press 2 (to select the USB Drive) and KaOS Linux will boot from the USB Drive.
I created this article per a user request. This was my first encounter with KaOS Linux and overall it appears to be a well thought out distribution.
Although I have not yet tried it this same technique can allow booting other Linux distro’s such as Ubuntu, or Kali.