MLG CREW RESPONDS CONTRARY TO TCASII RA INSTRUCTIONS.

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WE WERE CLRED DIRECT TO THE ARPT FOR RWY 8L. APCH CALLED VFR TFC BELOW US WHICH WE CLRED ABOUT 6 NM E OF THE FIELD. ALTHOUGH WE HAD A TCASII RA; I ACQUIRED THE TFC VISUALLY AND THE FO MINIMIZED THE RESPONSE TO THE RA BY REDUCING THE DSCNT RATE DOWN TO 6000 FT; OUR ASSIGNED ALT. APCH THEN CLRED US TO ENTER DOWNWIND N OF THE ARPT FOR RWY 8L. WE THEN HAD A PROGRESSION FROM A TA TO RA FOR TFC ABOVE US. WHILE SEARCHING FOR THE TFC; THE ALT ALERT SOUNDED; INDICATING THAT WE WERE 400-500 FT BELOW ASSIGNED ALT. MY REACTION WAS TO ADVANCE THE THROTTLES AND PICK THE NOSE UP TO RETURN TO 6000 FT. THIS WAS REINFORCED BY APCH CALLING AND ASKING US TO CHK OUR ALT; ASSIGNED 6000 FT. IT WASN'T UNTIL THE RA INCREASED IN INTENSITY THAT I PULLED THE THROTTLES BACK AND PUSHED THE NOSE BACK OVER AND DIRECTED THE FO TO RESUME THE PROPER RESPONSE TO THE RA. I IMMEDIATELY ADVISED APCH OF OUR ALTDEV DUE TO THE TCASII RA. APCH ADVISED US THAT THE VFR TFC HAD ALLOWABLE VERT SEPARATION ON US AND WAS PUZZLED BY THE RA OUR TCASII GAVE US. WE WERE THEN CLRED FOR THE VISUAL APCH RWY 8L; MAINTAIN 4000 FT UNTIL ON BASE; 3000 FT UNTIL ON FINAL. WE RECEIVED 3 MORE RA'S FROM DIFFERENT ACFT IN THE VICINITY BY THE TIME WE ROLLED OUT ON FINAL. SO WITH THE 5 RA'S AND SEVERAL (I LOST TRACK) TA'S; THERE WAS MORE THAN ENOUGH CONFUSION FOR 1 APCH. THE FO DID A GOOD SOLID JOB OF FLYING AND RESPONDING PER THE COMPANY'S PROCS. I FELT LIKE I DID MORE REACTING THAN PLANNING ON MY PART. I AM CONCERNED THAT MY REFLEX ACTION TO INITIATE A CLB BACK TO 6000 FT WAS CONTRARY TO RA'S DIRECTIVE. THE MULTIPLE RA'S AND TA'S POINT UP A SIGNIFICANT PROB. THE TCASII PARAMETERS FOR AN RA ARE STILL TOO BROAD; ESPECIALLY IN THE TFC PATTERN. I SPOKE TO THE APCH CTL SUPVR; WHO HAD BEEN LOOKING OVER THE CTLR'S SHOULDER DURING OUR APCH. HE SAID ALL THE VFR TARGETS HAD ADEQUATE SEPARATION FOR THE CTLR'S SEQUENCING. HE SAID A MORE PROMPT CALL ANNOUNCING THE DEV FROM ASSIGNED ALT WOULD HAVE PREVENTED THE CTLR'S QUERY ABOUT THE ALTDEV. I AGREED. COCKPIT COMS BTWN THE FO AND MYSELF HAD BEEN GOOD THROUGHOUT THE 3 DAYS WE HAD BEEN FLYING TOGETHER. THE CONVERSATION GOT BRIEF DURING THE APCH DUE TO ALL THE DISTRS. WE HAD A CHANCE TO DEBRIEF THE APCH AT LENGTH. THE 1 REAL IMPROVEMENT WE CAME UP WITH TO OUR COORD IN THE COCKPIT IS THE NEED TO VERBALLY STATE INTENTIONS TO RESPOND TO AN RA. I AGREE THAT RESPONDING TO AN RA SHOULD BE SELF-EXPLANATORY; BUT IN THIS CASE; WE HAD JUST CLRED TFC BELOW US WHEN A NEW TA TO RA SOUNDED FOR TFC ABOVE US. I WAS STILL WATCHING TFC PASSING BEHIND US; WHILE THE FO WAS REACTING TO TFC AHEAD. THE FO WAS AHEAD; I WAS BEHIND AND IT TOOK A MOMENT TO GET BACK TO THE SAME POINT.