Simply add the line:
exec .1.3.6.1.4.1.18689.1.69 qcheck /script/qmtool -s -Q
to the end of your Net-SNMP's /usr/local/share/snmp/snmpd.conf file,
accounting for which path you've placed the qmqtool script in.

> mkdir -p ~cricket/cricket-config/mailq/
> cp contrib/cricket/Defaults ~cricket/cricket-config/mailq/
> cp contrib/cricket/Targets ~cricket/cricket-config/mailq/
# edit your Defaults file to ensure the proper snmp-community.
# edit your Targets file to match your needs.
# put /mailq in your ~cricket/cricket/subtree-sets
> chown -R cricket ~cricket/cricket-config/mailq/
> ~cricket/cricket/compile