If you have the LWP package installed (and it would seem that you do, you can manually do what you want with the included 'lwp-request' script. It has a '-H' switch that lets you set arbitrary headers.

In a script, you can do something like:

#!/usr/bin/perl -w
use strict;
use LWP::UserAgent;
use HTTP::Request;

my $ua = LWP::UserAgent->new;
my $rq= HTTP::Request->new(GET => 'http://place.to.go.web/');
$rq->header("Cookie", "username=Joe"); # see this?
my $res=$ua->request($rq);

print $res->as_string
[download]

--
$you = new YOU;
honk() if $you->love(perl)