4.3BSD/usr/contrib/X/doc/installation/in.4

.NH
Installation Under 4.2BSD
.PP
You are essentially on your own here.
Besides the steps outlined in sections one through three,
you must install the Vs100 device driver,
install an improved version of the pseudo-tty driver,
and even then you will run into an obscure TCP problem that will
cause X to be unreliable.
.PP
We have also decided that it is hazardous for most people to attempt 
installation of the changes to init, getty and login required for automatic
login on the display.
Furthermore, due to local changes and version skew, we no longer have
a consistent set of sources for these programs for 4.2, and have no good
way to test any installation directions as we have been running these
changes for nearly a year on all our machines.
For these reasons, WE RECOMMEND UPGRADING to 4.3BSD or Ultrix 1.2 where
these changes are standard.