Hi Michael,
The out-of-box Update Status activity notification (which is where I would normally start for a requirement like this) in my r17 instance is not available for CIs. So you may have to start by creating an Activity Association for the CI status field, then add an Activity Notification, create an Event and an Exec PAM macro for it to launch, and tie them all together. You can control whether it fires for particular CI Families by creating a Condition macro for the event.
Let me know if you're having trouble following the chain.
Regards,
James