The Mason home page, from which you can download the latest version of Mason (and Mason-CM), subscribe to the e-mail list and read through documentation, is at http://www.masonhq.com/.
Philip Greenspun, whose book Philip and Alex's Guide to Web Publishing remains an excellent discussion of how to build web-based services, has written an article on the use of CVS and the Web. A large part of the article answers the question, “How can I take advantage of version control along if my application uses a database?” While this is not directly related to Mason-CM, it is excellent food for thought. You can read it at http://www.arsdigita.com/asj/cvs.
Two other good articles on the topic of CVS and web development are at http://durak.org/cvswebsites/ and http://www.daemonnews.org/199903/websites.html.
You can retrieve all the Perl modules required for use of Mason-CM from CPAN (the Comprehensive Perl Archive Network), a distributed network of FTP sites. Find the CPAN mirror nearest you by going to http://www.cpan.org/. Alternately, use CPAN.pm, which comes with every version of Perl.