UCSC WikiLab WikiThere are two ways of contributing to WikiTrust, depending on your affiliation:
Contributing to WikiTrust for External Developers explains how to contribute to WikiTrust if you are an independent developer.
Contributing to WikiTrust for UCSC WikiLab Members explains how to contribute to WikiTrust if you are a UCSC Wiki Lab member.
In both cases, have access to the full up-to-date version of the code; the only thing that changes is the way to get it, and to contribute back your changes. UCSC Wiki Lab contributors can use a shared git repository, which is slightly more convenient; external contributors need to submit patches, or (much better), set up their own public git repositories.
Some of the technical discussion on WikiTrust implementation is taking place in the Developer's Corner.