One Button to rule them all

Hi guys,
I want to have a _btn or _mc on stage that, when continuously clicked, loads sequential JPEGs from the library via attachMovie and tween fade it in. I can comfortably do that with a _btn per JPEG but do not know how to code for one _btn for, say, 20 JPEGs.
I hope I am making some sense. As ever, any help much appreciated.
Geminian1.