FLC FAILED TO SWITCH TO NEW FREQ ON APCH TO LNDG.

Narrative

APCHING BOIDS INTXN; ON INITIAL CONTACT WITH DFW APCH; WE WERE TOLD TO 'TURN TO 110 DEG HDG AFTER BOIDS; INTERCEPT RWY 13R LOC; DSND FROM 9000 FT TO 5000 FT; AND CALL ANOTHER APCH CTL ON 118.9.' FO WAS FLYING AND WAS NOT SET UP FOR RWY 13R ALTHOUGH HE HAD BRIEFED A VISUAL APCH TO THAT RWY. IN MY HASTE (CAPT; PNF) TO GET HIS NAVAIDS SET UP; SET THE FMS; AND COMPLETE THE APCH CHKLIST; I SOMEHOW FORGOT TO CALL ON 118.9. AT 5000 FT I NOTICED WE WERE JUST ABOUT ON THE RWY 13R GS SO I REQUESTED LOWER AND WE WERE TOLD AGAIN TO CALL APCH ON 118.9. WHEN I SWITCHED OVER TO 118.9; THE APCH CTLR WAS CALLING US TO SLOW TO 170 KTS AND DSND TO 4000 FT. WE ACKNOWLEDGED THIS AND ALSO CALLED THE ARPT IN SIGHT; AFTER WHICH HE ISSUED A VISUAL APCH CLRNC. TO OUR KNOWLEDGE THERE WAS NO CONFLICT. CONTRIBUTING FACTORS: 1) MY FAILURE TO INSURE FO HAD HIS NAV RADIOS SET UP DURING HIS APCH BRIEFING; AND 2) INITIAL DFW APCH CTLR GIVING MORE THAN 3 INSTRUCTIONS IN A SINGLE XMISSION WITH AN IMMEDIATE FREQ CHANGE. PREVENTION: IN THE FUTURE; INSURE WE ARE COMPLETELY SET UP FOR THE CLOSEST PROBABLE APCH EARLIER IN THE DSCNT.