[ableasby at hgmp.mrc.ac.uk]

Your problem is indeed that Apple don't supply a full X11, there are
no development headers etc.

Other MacOSX users may be able to advise better than I on this,
however I compile it on that platform using the Xfree binaries
from (picking a USA mirror site for you):

 ftp://ftp.mirrorcentral.com/pub/XFree86/4.2.0/binaries/Darwin-ppc-5.x/

Get all the tgz files and Xinstall.sh. Then run Xinstall.sh which will
unpack the tgz files and install everything.

I have not tried installing it over the top of Apple's version so
you'll have to consider whether you wish to clean up first.

HTH

Alan Bleasby
HGMP