Ok, I've determined that I'm actually asking the wrong question. The above will work when I supply the exact name of the manual script:
e.g. Set strTemp = TestName.GetStepInfo(intStepID).
So the real question I have is how do I pass the test name into the Event. I assume that the Sender object has the data, but I've been unable to determine the command needed to extract it, and the help files have not been helpful.