You can obtain the very latest version of µCode by accessing the CVS source repository hosted by SourceForge. Be aware that such source image is not necessarily consistent, and hence working.
Detailed instructions about how to get anonymous read access to the repository are available at the repository. This kind of access is available to anyone. On the other hand, if you want to contribute code to the µCode repository you need write access to the repository, which is granted only to registered µCode developers. To become a registered developer, just contact me, illustrating what you would like to contribute and/or work on.