You can download the pkgsrc package of xml2doc for NetBSD [ here ].
If you have problems building xml2doc on NetBSD try these flags:
env CPPFLAGS=-I/usr/pkg/include \
CFLAGS=-I/usr/pkg/include \
LDDFLAGS=-L/usr/pkg/lib \
./configure --prefix=/usr/pkg && \
gmake install
Thx to xtraeme and jmmv from #hispabsd on freenode. :)