Are you asking about mod_perl? 'Regular' Perl (including the CGI module) doesn't need to be configured for Apache. Though Apache does need to be configured to allow cgi scripts.
I don't remember the specifics off the top of my head but basically there's a SetHandler line in the Apache conf file (which I believe comes commented out...) to the effect of:
SetHandler cgi-script cgi
where 'cgi-script' tells Apache to handle anything with an extension of 'cgi' (and you can add other extensions such as 'pl') as a cgi program.
There's a couple Apache configuration books out there - including O'Reilly's - that will explain it better than me.