The user places the request using LWP (LWP::UserAgent, even) rather than HTTP::Request, as shown in the following example:

use HTTP::Request::Common;

$ua = LWP::UserAgent->new;
$ua->request(POST 'http://example.com/survey.cgi', [
   name   => 'Gisle Aas',
   email  => 'gisle@aas.no',
   gender => 'M',
   born   => '1964',
   perc   => '3%',
]);
[download]

HTTP::Request could have been used instead of HTTP::Request::Common.