Hey Jeff!
Hope you don't mind, I've been toying around with doing some Xpression tutorials, so I figured I'd respond to you in Video format!
https://youtu.be/eZjvzvOiKpE
Here's the script in the code block:
dim Headshot as xpQuadObject
dim Material as xpMaterial
Scene.GetObjectByName("Headshot", Headshot)
Headshot.GetMaterial(0, Material)
Material.SetPlayMode(PlayMode.pm_Once)
Material.Play()
Let me know if that's not how it's supposed to look or if I should define something differently!
#XPression