Before using multimon and the other CGI programs, first ensure that
apcupsd is configured to run the Network Information Server. This is
done by setting NETSERVER on in ${SYSCONFDIR}/apcupsd/apcupsd.conf. 
This switch is on by default.
To run scripts in chrooted apache (default behaviour) you need to 
copy some files to /var/www/, preserving hierarchy:
${SYSCONFDIR}/apcupsd/apcupsd.css
${SYSCONFDIR}/apcupsd/hosts.conf
${SYSCONFDIR}/apcupsd/multimon.conf
${LOCALBASE}/lib/libgd.so.*
${LOCALBASE}/lib/libiconv.so.*
${LOCALBASE}/lib/libjpeg.so.*
${LOCALBASE}/lib/libpng.so.*
${X11BASE}/lib/libexpat.so.*
${X11BASE}/lib/libfreetype.so.*
${X11BASE}/lib/libfontconfig.so.*
/usr/lib/libc.so.*
/usr/lib/libm.so.*
/usr/lib/libpthread.so.*
/usr/lib/libz.so.*
/usr/libexec/ld.so