If you want to put a version on CPAN but don't want the general CPAN shell users to try to installing it, put a `_' in the version number (e.g. 0.40_01) in the tarball name. CPAN.pm will ignore that version unless it's explicitly requested (install F/FO/FOO/MyModule-0.40_01.tar.gz). Check perldoc CPAN for (slightly) more detail.