use LWP::UserAgent;

$ua = new LWP::UserAgent;
$ua->proxy(['http', 'ftp'] => 'http://proxy.myorg.com');

$req = new HTTP::Request 'GET',"http://www.perl.com";
$req->proxy_authorization_basic("proxy_user", "proxy_password");

$res = $ua->request($req);
print $res->content if $res->is_success;