Make sure to hit up their IRC first, the friendly folks there will put you into the right path. Krita will always be special for me because I’ve put in a feature that I use all the time. So it will become special for you as well.
I'm not familiar with the project either, but ensure it is a feature they intend to accept into their project before you commit the energy into developing it. I have had a weekend that was devoted to naught because it wasn't aligned with the vision or roadmap.