Here we have two different versions of X11 for Xenix.

X11R5 is actually a binary compiled version, but it needs a socket emulation library
by Chain Lee and I don't have it. It used to cost 30 bucks, I don't have an email for this
guy but he probably  used to live in Holton Road 11, Lexington, MA. If you dare calling 
every Mr. Lee in Lexington... you're welcome.

X11R4+X386 is a source of the WHOLE X11R4 distribution+patches+X386 patch+specific xenix
patches by Per Lindvquist. I got them from Usenet, but I never managed to compile them.
If you do, write me! scoxenix@gmail.com 

From comp.unix.xenix.sco, "Help getting X11R4 working on SCO Xenix"
https://groups.google.com/forum/?hl=en&fromgroups=#!searchin/comp.unix.xenix.sco/per$20lindqvist/comp.unix.xenix.sco/SnYrjq-x32A/oiCiYqQ7tHsJ