[//Delta//msidmPamRequestRole] was all that was needed. So I was able to determine the msidmPamRole/Owner and from that determine the email address of the msidmPamRole/Owner to inject into the 'To' recipient of the MIMWAL Send Email Notification Activity.
Notes:
Combining the Resource Lookups with the Email Notification Activity proved to be problematic...so I separated them out into separate steps in the Workflow.
It works fine when there is a single Owner for msidmPamRole...but fails when there are multiple Owners. Will post how to do this when I figure it out unless anyone else already knows.