Advanced preloading

I have read the tutorials I preloading in FLash MX 2004 on Kirupa, that are great by the way, but I was wondering if anyone had an idea as to how to make a movie clip (like a plant growing) and use AS to make is do, depending on the percentage loaded, the movie clip stops and starts but still, when the SWF is done loading, the movie clip has finished too? Do you guys understand what I am trying to say? Thanks.