Here you go:
And this is the plugin:
#!/bin/bash
# Log Event to Logfile
LOGFILE=/var/log/checkmk/checkmk.log
echo "New Event" >> $LOGFILE
if [ $NOTIFY_WHAT == SERVICE ]
then
echo $NOTIFY_LONGDATETIME type=\"SERVICE\" address=\"$NOTIFY_HOST_ADDRESS_4\" alias=\"$NOTIFY_HOSTALIAS\" hostname=\"$NOTIFY_HOSTNAME\" service=\"$NOTIFY_SERVICEDESC\" state=\"$NOTIFY_SERVICESTATE\" output=\"$NOTIFY_SERVICEOUTPUT\" >> $LOGFILE
elif [ $NOTIFY_WHAT == HOST ]
then
echo $NOTIFY_LONGDATETIME type=\"HOST\" address=\"$NOTIFY_HOSTADDRESS\" alias=\"$NOTIFY_HOSTALIAS\" hostname=\"$NOTIFY_HOSTNAME\" state=\"$NOTIFY_HOSTSTATE\" output=\"$NOTIFY_HOSTOUTPUT\" >> $LOGFILE
fi
exit 0