#!/usr/bin/perl
use SOAP::Lite +trace;

$login='log';
$passwd='passwd';
$domain='dom';

sub SOAP::Transport::HTTP::Client::get_basic_credentials {
   return $login => $passwd;
      }

$tab = SOAP::Lite
               -> service('http://url.wsdl')
               ->getDomUsedQuota($domain);
...