use LWP::UserAgent;
use HTTP::Cookies;
use HTTP::Request::Common qw(POST);

my $ua = new LWP::UserAgent;
my $cookie_jar = new HTTP::Cookies;

$cookie_jar->add_cookie_header($ENV{HTTP_COOKIE}); #This line is troublesome
my $req = POST 'http://foo.com/cgi-bin/log_cookie.cgi',
                [ data => 'somedata', errors => 'probably' ];

 print $ua->request($req)->as_string;