boot from remote device?

[James Frew]

I have a standalone VAXstation 3100 running UWS 2.0 (== ULTRIX 3.0).
ULTRIX was installed from CDROMs.

I also have 2 standalone VAXstation IIs running ULTRIX 2.0.  These
each have a TK50 and an RD53.  ULTRIX was installed from TK50s.

All 3 of these machines are hooked to the same Ethernet.

I would like to bring up 3.0 on the VAXstation IIs.  The 3100 doesn't
have enough disk space to run the IIs diskless.  Needless to say, I
don't have 3.0 on TK50s.  SO:

-- Is there some way to boot ULTRIX from a remote device (like Sun lets
   you do from a remote tape drive)?

or

-- How do I create a 3.0 boot TK50 from the save sets on the CDROM?  I
   don't need a complete system, just a root; I CAN share the 3100's
   /usr.