you can use the currentFrame and totalFrames properties of movieclips to do that.
for example, for a horizontal progress display (progress_bar with fill_mc where fill_mc has left side reg point);
var mc = this movieclip whose timeline play-progress you wish to display
Maybe it's been fixed by now, but when I first tried doing this sort of thing, I found the "official" properties to not be reliable. That's why I use these instead:
this.timeline.position (instead of this.currentFrame)
this.timeline.duration (instead of this.totalFrames)