Permanently booting from a USB stick

Hi,
I'm planning to build a small FreeNAS station using this board:

http://www.sapphiretech.com/presentation/product/?cid=2&gid=1047&sgid=1045&pid=1662&psn=&lid=1&leg=0

Since it has only 4 SATA ports and I want to use them for 4x 1TB HDDs I wonder if it's possible to install FreeNAS on a fast USB stick and boot from it permanently.
Generally I would like to avoid buying another SATA controller just for the boot drive.

Just in case this is a feasible way to run FreeNAS I still have...

Permanently booting from a USB stick