If I asked an artist to make me an icon I wouldn't expect to need to write code to convert a .3DS model into a usable icon format.
You can save yourself a lot of time and hassle by having your designer use File->Export and give you PNGs of the layers and frames instead of a .FLA file if that's the format you require for your implementation.
If that's not possible for some reason then you can probably find a flash decompiler that has a command line option which you could launch from your program to extract assets as part of your loading sequence but that is generally frowned upon because this is not the intended use of the proprietary format for .swf/.fla anymore than you should design applications to extract source code from a binary executable.