Contributions are managed most easily via pull requests. This project is hosted at https://github.com/comcast/tsb . Head over, fork the project and open a pull request.
If you run into any problems or have ideas for features (even if you can't personally implement them!), please open an issue on GitHub. Bug reporting and feature design is a great way to get involved with this project.
Weasel currently vendors all known dependencies. It's possible that this may change in the future, but unless there is a compelling reason, any new dependencies should also be appropriately vendored.