Resolution:
Use the functions TutGetOutputfunc and TutSetOutputFunc.

(NOTE the cast using T_ENTRY_VA. )
(This is not in the coding examples in the Utility Manual as of 6.4r2 . )

#include &ltrtworks/ipc.h>

T_OUT_VA_FUNC save_func;

// NOTE THE T_ENTRY_VA CAST - required for cross platform compatability.

static void T_ENTRY_VA redirect_io_func(T_STR format_str, va_list arg_list);

int main(void)
{
  save_func = TutGetOutputFunc(); // save address of function we use for screen I/O.

// Hide RTclient connection information.
TutSetOutputFunc(redirect_io_func);

TipcSrvCreate(T_IPC_CONN_FULL); // connect to RTserver

TutSetOutputFunc(save_func);    // restore address of function which uses screen I/O .

// Real application work goes here.

TipcSrvDestroyT_IPC_SRV_CONN_NONE);

TutExit(T_EXIT_SUCCESS);
}

// Function to quiey Screen I/O

static void T_ENTRY_VA redirect_io_func(T_STR format_str, va_list arg_list)  
  {
   // do_nothing and return. Remember, you first have to do_nothing :)
   return(T_EXIT_SUCCESS);
  }

How can I turn off the RTclient connection output on stdout?