To do this, you’ll need access to command line/terminal. You can use just about any Linux Live CDs (including Ubuntu's) but I personally went for the System Rescue CD. After installing CloudReady on your harddrive as usual, boot from the live CD and enter the following into the terminal:
parted /dev/sda disk_set pmbr_boot onReboot the machine and should be able to boot from your Chromium OS. I spend solid 3 days trying figure this out and my OCZ Agility 3 died in the process, hopefully you'll find this useful.