Решение такое:
IdTCPClient1->Host = "localhost";
IdTCPClient1->Port = 8887;
IdTCPClient1->Connect();
IdTCPClient1->IOHandler->WaitFor("Login:");
IdTCPClient1->IOHandler->WriteLn("1");
IdTCPClient1->IOHandler->WaitFor("Password:");
IdTCPClient1->IOHandler->WriteLn("1");