David Coe & Pierre Humblet write:

To run man with Cygnus cygwin B20.1 you will need groff and associated
utilities, for example from

ftp://ftp.franken.de/pub/win32/develop/gnuwin32/cygwin32/porters/Hirmke_Michael/B20/groff-1.10-cygwin-b20-bin.tar.gz

Adjust the paths in configure and man2html/Makefile.in to suit your
installation.

man-1.5f builds with:
    CC="gcc -DNONLS -DLC_MESSAGES=6" ./configure -d +traditional
then issue:
    make
then:
    make install

Edit the installed man.conf to suit your site.