Hi,
Well i have a 600au running with Xfree86-4.2.1 server, 
what i did to get it:
1) downloaded xfree.tar.gz from ftp.netbsd.org
make World in /usr/xsrc/xfree/xc... Test to see if it will 'make'
complete.
make clean
edit /xsrc/xfree/xc/programs/Makefile ~line 223, EXTRA+LOAD_FLAGS = -W1,
-Bstatic
edit /xsrc/xfree/xc/programs/Xserver/Makefile as above.
replace /xsrc/xfree/xc/programs/Xserver/.../os-support/bsd/bsd_video.c
with enclosed bsd_video.c( e-mail me for copy)
Also enclosed is /var/log/XFree86.0.log (e-mail me for copy)from this
machine.
I have been up for 2HRS, not much on this HD to test at the moment
but i will push it to 'ogle' fairly soon(i hope..with accelleration).
2)return to 'text mode' is a work in process but Xserver builds and runs
....can't wait to test my ati 'radeon pci cards 32MB vram......
Have fun -Mel