Missing xf86cfg?

Noob question - my installation of NetBSD 3.1 is working fine, and I can start X fine, on a PenCentra 130. But I'd like to tweak my XF86.config file. I can't find anywhere:

f86cfg
xf86config
xorg.conf

nor any of the usual xf86 config files. But X is there, and works...

and using "X -configure" to create an XF86 config file complains that "-configure" isn't a valid option".

What am I doing wrong?

thanks,

Peter B.