[AS3] Simple Event problem

Now, my experience with AS3 isn’t huge, I can do most things, but I’ve become stumped by what I think must be one of the simplest and silliest of problems.
How would I add an EventListener so that when the movie is loaded it automatically executes a function?
Surprisingly, I’ve never had to do this in the same way before, usually I can just piggyback off loader events to get this going.
Anyone able to tell me how to get this going?