define contact {
       contact_name                             pagerduty
       alias                                    PagerDuty Pseudo-Contact
       service_notification_period              24x7
       host_notification_period                 24x7
       service_notification_options             w,u,c,r
       host_notification_options                d,r
       service_notification_commands            notify-service-by-pagerduty
       host_notification_commands               notify-host-by-pagerduty
       pager                                    <YOUR SERVICE KEY HERE>
}

define command {
       command_name     notify-service-by-pagerduty
       command_line     /usr/local/bin/pagerduty_nagios.pl enqueue -f pd_nagios_object=service
}

define command {
       command_name     notify-host-by-pagerduty
       command_line     /usr/local/bin/pagerduty_nagios.pl enqueue -f pd_nagios_object=host
}