Bill, I ran into the same issue. Catalyst is really a tool for building an GUI for Flex apps. Even though you can get some simple apps working the inability to target states in nested components limits what you can do.The goal of version 1 was not what you want to do with it.
You really should import the project into flash builder to add advanced code like that. There you can flesh out your components and add event listening/ dispatching for things like onLoad etc...
Thanks very much for your reply, I'll find a way to overcome it now that I know its a limitation of the application.
Have a good one,
I know this is an old post but I just started using Catalyst yesterday and figured out (I think) to do what you are looking for. Initially all I found were mouse events and I am building a sliding logo so I just wanted the onload event. Since all I saw were mouse events when I clicked the add interation, I closed that and clicked the word "Application" next to that button. Amazingly, now the list has "On Application Start". It has the same results as "onload"
If you transfer the project into Flash Builder, you can programmatically listen for a variety of start up events.