HTTP/1.1 407 (Proxy Authentication Required) Proxy Access Denied
   # stuff we don't need to know deleted.
   Proxy-Authenticate: NTLM 
   Proxy-Authenticate: Basic realm="..."
   Client-Warning: Unsupported authentication scheme 'ntlm'

##</code><code>##

   use LWP::UserAgent; 
   $ua = new LWP::UserAgent;
   $ua->proxy(http => 'http://proxy.example.com:80'); 
   $ua->proxy_authorization_basic( 'username', 'password' );
   my $req = new HTTP::Request ('GET', 'http://www.yahoo.com/'); 
   $page = $ua->request($req)->as_string; 
   print $page;