Fergus,

See

http://sources.redhat.com/ml/cywin-xfree/2004-02/msg00158.html

and 

http://sources.redhat.com/ml/cywin-xfree/2004-02/msg00185.html

I undertand that the only way to make xman function properly is to
modify the script /bin/nroff in order to force the -c option. That is not
a clean solution. What should be done is to modify Xman in order to
include the -c option when Xman calls nroff. I believe that that
should be done by the XFree mantainers. In any case in the attachment
there is the modified nroff.

Rodrigo Medina