program  ntlmdemo;

 {$APPTYPE CONSOLE} 

 uses 
  SysUtils,
  IdAuthentication,
  IdAuthenticationNTLM,
  IdHTTP;

 type 
  TDummyProxy =  class 
   private 
     class   procedure  OnProxyAuthorization( Sender: TObject;
      Authentication : TIdAuthentication;  var  Handled : Boolean );
   end ;

 { TDummyProxy } 

 class   procedure  TDummyProxy.OnProxyAuthorization(Sender: TObject;
  Authentication: TIdAuthentication;  var  Handled: Boolean);
 begin 
  Authentication.Reset;
  Authentication.Username := '...';
  Authentication.Password := '...';
  Handled := true;
 end ;

 begin 
   with  TIdHTTP.Create(  nil  )  do 
   try 
    OnProxyAuthorization := TDummyProxy.OnProxyAuthorization;
    ProxyParams.ProxyServer := '...';
    ProxyParams.ProxyPort :=  3128 ;
    ProxyParams.BasicAuthentication := false;
    HTTPOptions := HTTPOptions + [ hoInProcessAuth ];
    WriteLn( Get('http://ya.ru') );
   finally 
    Free
   end ;
 end .