DIRTSAND is developed by H'uru on Github. If you wish to contribute, you can fork the repository and submit pull requests with your modifications. DIRTSAND is currently quite feature complete; unavailable features such as Heek are due to intentional design decisions.
DIRTSAND can be built from source for Linux (and possibly other *nix) OSes. Follow the getting started guide to build DIRTSAND for your system. You'll need Git to fetch the sources.
The process for contributing to DIRTSAND is essentially the same as for Plasma.