cd src; make install
install -c  man /usr/local/bin/man
install -c -m 755 apropos /usr/local/bin/apropos
install -c -m 755 whatis /usr/local/bin/whatis
install -c -m 754 makewhatis /usr/local/sbin/makewhatis
install -d /usr/local/lib
if [ -f /usr/local/lib/man.conf ]; then mv /usr/local/lib/man.conf /usr/local/lib/man.conf.orig; fi
install -c -m 644 man.conf /usr/local/lib/man.conf
cd man2html; make install
install -m 755 man2html /usr/bin
mkdir -p /usr/local/man/man1
install -m 644 man2html.1 /usr/local/man/man1/man2html.1
cd man; make installsubdirs

==== Installing the english man pages. ====
mkdir -p /usr/local/man/man1 /usr/local/man/man5 /usr/local/man/man8
for i in man whatis apropos; \
        do install -c -m 644 $i.1 /usr/local/man/man1/$i.1; done
for i in man.conf; \
        do install -c -m 644 $i.5 /usr/local/man/man5/$i.5; done
for i in makewhatis; \
        do if test -f $i.8; then install -c -m 644 $i.8 /usr/local/man/man8/$i.8; fi; done

==== Installing the japanese man pages. ====
mkdir -p /usr/local/man/ja_JP.ujis/man1 /usr/local/man/ja_JP.ujis/man5 /usr/local/man/ja_JP.ujis/man8
for i in man whatis apropos; \
        do install -c -m 644 $i.1 /usr/local/man/ja_JP.ujis/man1/$i.1; done
for i in man.conf; \
        do install -c -m 644 $i.5 /usr/local/man/ja_JP.ujis/man5/$i.5; done
for i in makewhatis; \
        do if test -f $i.8; then install -c -m 644 $i.8 /usr/local/man/ja_JP.ujis/man8/$i.8; fi; done
cd msgs; make install
sh ./inst.sh " en ja_JP.ujis" "/usr/share/locale/%L/%N"
mkdir -p /usr/share/locale/en
install -c -m 644 mess.en.cat /usr/share/locale/en/man
mkdir -p /usr/share/locale/ja_JP.ujis
install -c -m 644 mess.ja_JP.ujis.cat /usr/share/locale/ja_JP.ujis/man

Done.
In case you want to browse man pages using a www browser,
"cd man2html", read README, and perhaps "make install-scripts".