See:
   http://mail-index.netbsd.org/port-macppc/1999/10/31/0000.html


I do not recommend to setuid, but if you insist to do that,
   chmod 4711 /usr/X11R6/bin/X 
to get following permission.
-rws--x--x  1 root  wheel  7361618 Oct 29 11:49 /usr/X11R6/bin/X

My recommedation is to use xdm, which you need
(1) Have root passwd set
(2) xdm=YES  in /etc/rc.conf
and adjest ~/.xsession for your initial screen layout. 

http://www.netbsd.org/Ports/macppc/faq.html
---
Makoto Fujiwara
http://www.ki.nu/software/NetBSD/iBook2/