Boot into Chromium OS from the USB.
At the set up screen, enter a developer terminal by pressing
Here you will be asked to log in. Use the follow credentials:
You will then need to enter the following command.
You will then be asked to confirm the password.
Now that you have super user rights you can now install to the required hard drive of your choice.
To find out what drive you need to install to, use the following command:
fdisk -lThis will list all the disks connected to your computer.
Find the hard drive you want, this may be hard and take some working out from the hard drive sizes.
Once you know what drive you wish to install to, look for its drive mapping. This will look something like /dev/sda.
Now you know your drive mapping you can run the command:
chromeos-install --"drive mapping"I.e "chromeos-install --/dev/sda"
This will now install Chromium OS to your selected hard drive.