No documentation.  I have to finish the PXE stuff to make it a little easier.
Right now, I use PXE to get a 9load and then type the real kernel address
by hand when 9load prompts.

What I intend to do is have an extra entry in the ndb that indicates which
file to download for PXE and which for 9load.  I can distinguish using the
vendor id (or some such).  I'm on vacation but I'll finish it when I get back,
not a lot of work.