mod_perl and all the various Perl modules and helper utilities mentioned in this book are available via FTP and HTTP from any of the sites on the Comprehensive Perl Archive Network (CPAN) at http://cpan.org/. This is a list of several hundred public FTP and HTTP sites that mirror each others' contents on a regular basis.
You can search for and install Perl modules in two ways:
Manually, by going to http://search.cpan.org/, finding the module, then downloading, building, and installing it. You can also browse the modules by categories or authors at http://cpan.org/.
Automatically, by using Andreas Koenig's CPAN shell or (on MS Windows systems) the Perl Package Manager (PPM). These tools allow you to search for available modules and install them with a single command.