I searched web and found a VMWare virtual disk of ChromeOS here. So I downloaded it.
Not wanting to install VMWare, I converted it to a raw disk image and loaded it to XEN with HVM, it worked. But it basically unusable for me mainly because of mouse movement was too slow. I will try with a different vnc client later to see if it improves.
Here's how to convert vmdk image to raw:
$qemu-img convert -f vmdk chrome-os-0.4.22.8-gdgt.vmdk -O raw chrome-os.img
Then just specify the image file in 'disk' line of domain config file, like:
disk = [ 'file:/root/chrome-os.img,hda,w' ]
Here's screenshot of chrome OS:
Here's chrome OS login screen, I have a Fedora 12 hvm domain and a Ubuntu 9.04 32bit domainU also running on this machine. The domain0 itself is Fedora 12 64bit with pvops kernel 220.127.116.11.
I had to use standard VGA driver(stdvga=1), the default Cirrus Logic driver give me a screen like this after I login: