you can set up a custom event.
hit F2 then go to the eventmanager tab.
here you can pretty much do anything.
you add an event then name it something like or whatever. Then you will add command or triggers under that event. make since?
the event plays in the order of hierarchy. so if you use the timer it starts when it gets to that line.
then in the skin editor (pause/break) you make your button play your custom event by assigning the new event on the button you want.
BUT,
if all you want to do is add dim then you can select the play movie event and open it then add the girder string.
I bet this is as clear as mud. Sorry.