Well I wasn’t making a game but I just went through what the author describes: finishing up the app, gotta set up the preloader. I did a manual version of this but I like this idea. However I am not using FlashDevelop. 
I am in the Flash IDE for compiling. I have thought of being able to just embed assets from Flash CS3 into a Flexbuilder / Flashdevelop AS3 project. And it seems to be becoming a popular thing to do.
gamepoetry » The Last Preloader You’ll Ever Need
Zero Effort Preloading
Based on the fundamentals established in the bit-101 article, I have
provided an AbstractPreloader class. You must subclass this class in
order to create a meaningful preloader for your game. These are the
steps required to get your preloader working:
Extend the provided AbstractPreloader class.
Override the following protected functions: beginLoading,
updateLoading( percent ), endLoading. If your Main class is not called
“Main”, then override the mainClassName function too.Embed the preloader with a single line of code.
Be mindful of gotchas.
That’s it, really.
the cleanest way to do a pure as3 preloader is here:
http://omar-fouad.net/blog/?p=69
which follows the FlashDevelop “ActionScript 3 Project with Preloader” template.
the only thing I do different than Omar is to name my Preloader class whatever my project is, so I get a WhateverProject.swf instead of another random Preloader.swf