There are several other Perl modules that you might wish to have installed, to take full advantage of mod_perl functionality. Provided you have Andreas König's CPAN.pm module, simply run:
cpan> install Bundle::Apache
This will fetch and install mod_perl and related packages for you all at once. Otherwise, once you've installed mod_perl see the listing by running
% perldoc Bundle::Apache
See also the source and the binary distributions.