dsw,
My experience in experimenting with this is that it seems like the lib command puts mylib at the end of the list of directories consulted--so that the perl interpreter finds my web host's outdated version of CGI.pm (Version 2.42) first & so doesn't load the version that I've stored at mylib. (The Perl script I've executed to verify the version number still prints out "Version 2.42" so the Perl interpreter seems to be still grabbing the web host's version)
Tom