Preloader for a externally loaded .jpg

buenas tardes

I need the script for a preloader for a externally loaded .jpg

I have a button with a gotoAndStop, to a frame where theres an empty movie clip that loads a .jpg… I want to add a percentage (in numbers) preloader… I know how the preloaders work for swf, but I dont get how to make the preloader work to get the bytes loaded of the image in the empty mc, called container.

One day Ill be able to answer many questions… for today, I still need to be answered…

Thank you very much

namaste