@ owen1204:
To help you, we need more information about your workflow. What settings did you use in Twilight to run the rendering of the SketchyPhysics animation?
Sorry, I don't know any way... maybe there is an adaptation of [1,2,3,4][(frame/50)%4] that changes when you press something. Variables need to be refreshed every frame, so no luck there... why not just use an emitter?