We've tried to make it easy to make changes to the code, even if you aren't familiar with Actionscript. You don't need Flash. You can download MTASC, a free software solution to compile AS2 code. Just drop the MTASC binary the source directory and, for example, you can build a new swf by entering something on the command line like:
./mtasc GraphLoader.as GraphVis.as -swf GraphGear.swf -version 8 -cp classes