重载TServerClientThread和它的protected ClientExecute
type 
  TServerClientThreadEx = class(TServerClientThread)
  public
    procedure ClientExecute; override;
  end;
  tform1 =class(TFOrm);
   ..
   procedure ServerSocket1GetThread(Sender: TObject;
     ClientSocket: TServerClientWinSocket;
     var SocketThread: TServerClientThread);
   ..
  end;
{TFOrm1}
procedure TForm1.ServerSocket1GetThread(Sender: TObject;
  ClientSocket: TServerClientWinSocket;
  var SocketThread: TServerClientThread);
begin
  SocketThread := TServerClientThreadEx.Create(False, ClientSocket);
end;{my TServerClientThreadEx}
procedure TServerClientThreadEx.ClientExecute;
begin
  //you code in here in single thread
end;