In addition to the tree Andrey noted, the general
answer is simply to download the normal distribution
image and use that. The effect is the same as using
the tree Andrey pointed to and updating, but you'll
save yourself time and work by just grabbing the
current image.

http://plan9.bell-labs.com/plan9/download/plan9.iso.bz2

just mount the image and copy the contents to
wherever you'd like your 9vx root to live, and point
9vx at that.