To start apcupsd at boot time, you must edit
${SYSCONFDIR}/apcupsd/apcupsd.conf and add the following lines to
${SYSCONFDIR}/rc.local:

if [ -x ${PREFIX}/sbin/apcupsctl ]; then
	echo -n ' apcupsd'
	${PREFIX}/sbin/apcupsctl start 2>&1 > /dev/null
fi

This will start apcupsd and use ${SYSCONFDIR}/apcupsd/apcupsd.conf for
the configuration. The ${PREFIX}/sbin/apcupsctl script can be used to
start/stop/restart apcupsd.

For more correct shutdown you should add following lines to
${SYSCONFDIR}/rc.shutdown script:

if [ -f ${SYSCONFDIR}/apcupsd/powerfail ]; then
  echo
  echo "APCUPSD will now power off the UPS"
  echo
  powerdown=YES
  echo
  echo "Please ensure that the UPS has powered off before rebooting"
  echo "Otherwise, the UPS may cut the power during the reboot!!!"
  echo
fi