FloodGrapher was built to be built on top of. Please do write plugins for the grapher or the robot, and also submit them to Kawigi (kawigi@yajags.com) for the next release. I tried to make it as simple and organized as possible to extend FloodGrapher, but that doesn't mean it's obvious how to do it, so these pages should give you a guide as to how to do what you want to do:
It may also be useful to read the documentation on FloodScript to do some of the things discussed in here