ActionScript 2.0 :: Creating A Flash Widget For A Client?

I am in the process of creating a Flash widget for a client. I am an accomplished Flash designer, but this particular project has got me stumped! The client absolutely loves the concept, but the current approach that I have taken just isn't practical. I have used Swift3D to produce the animated squares manually, and then pieced them together in Flash. This is fine for 6 squares, but the client wants the image to be divided up into about 100 squares, which translates into a lot of manual work! In addition, the SWF file is going to get very big very quickly due to all the frames needed for each square. Lastly, the client wants the option to change the images used at a later date, which simply isn't an option at the moment without starting from scratch.

I cannot think of an easy way around the above problems other than producing the animation at run time, which is what I am trying to do now. However, I can't think where to start! Ideally, there would be two JPGs which Flash would carve up into squares and animate itself but this is really pushing my abilities.