Detection rules for .pkg installers

I am working in Altiris 7.5 to deploy a Managed Software Delivery policy for SEP 12.1.5. I go to the Software Catalog and do an Import. When I import the software resource I notice the detection rule is not set automatically. When I import a software resource for an msi the detection rule is set automatically but when I import a .pkg it is not set. How can I setup a detection rule for Macs that will check if SEP 12.15337.5000 is installed? Thank you.