B737 CAPT REPORTS BEING OVERLY RESTRICTED BY COMPANY PROCEDURES PREVENTING MANEUVERING TO THE NORTHWEST DURING CIRCLING APPROACH TO MMZH RWY 26.

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I WAS QUITE FAMILIAR WITH MEXICO AIRFIELDS; BUT HAD ONLY BEEN INTO ZIH A COUPLE OF TIMES. MY FO HAD NEVER BEEN TO ZIH. THEY WERE CALLING SCATTERED CUMULONIMBUS IN THE AREA AND 5 MI VISIBILITY. STANDARD TROPICAL HAZE FOR MEXICO THIS TIME OF YR. WE WERE EXPECTING THE VOR DME-2 RWY 8 CIRCLE TO RWY 26; THUS EXPECTING A NICE L DOWNWIND TO CIRCLE TO RWY 26. THEY GAVE US THE VOR A WITH A CIRCLE TO LAND RWY 26 DUE TO DEPARTING TFC. THE APCH WAS NOT IN THE FMS DATABASE SO WE BUILT IT; AND FLEW IT WITH RAW DATA BACKUP. THE SLANT RANGE VISIBILITY WAS REALLY LIKE 3 MI. WE ADHERED TO THE COMPANY POLICY OF MAINTAINING 1000/3 FOR THE CIRCLE MANEUVER. I SAW THE FIELD AT 3 MI AND TURNED INTO DOWNWIND AT FLAPS 25 DEGS. BY THE TIME THE TURN WAS COMPLETED WE WERE ABOUT 2 MI ABEAM THE RWY. THE TERRAIN TO THE E CONCERNED THE FO SO I KEPT IT TIGHT AND LANDED ON RWY 26 UNEVENTFULLY. I FELT AS THOUGH THIS CIRCLING MANEUVER IS A DIFFICULT ONE WITH THE VISIBILITY THE WAY IT WAS. THE ARPT BRIEFING PAGE RESTRS OF NOT CIRCLING N SHOULD BE CHANGED TO ALLOW YOU TO OVERFLY THE FIELD AND THE NAVAID AND THEN ENTER A L DOWNWIND JUST LIKE THE MISSED APCH; THIS WILL SET YOU UP NICE AT 1000 FT MSL ON DOWNWIND WITH NICE LATERAL RWY DOWNWIND SPACING. THERE IS A 600 FT OR SO FT HILL THAT YOU WILL OVERFLY WHICH THE ARPT BRIEFING PAGE SAYS MIGHT CAUSE A GPWS. IF YOU FLEW THE 1500 FT RECOMMENDED PATTERN ALT ON DOWNWIND YOU WOULD LOSE SIGHT OF THE FIELD DUE TO THE VISIBILITY THAT DAY. CHANGE THE ARPT BRIEFING PAGE TO ALLOW YOU TO MANEUVER NW OF THE FIELD. THIS RESTR SEEMED TO LIMIT MY MANEUVERING REQUIREMENTS. I AGREE THAT MANEUVERING N OF THE FIELD SHOULD BE NOT AUTH. THE BEST CHOICE WOULD BE TO ASK FOR THE VOR DME-2 RWY 8 CIRCLE TO RWY 26. I FELT AS THOUGH THE CIRCLING MANEUVER IN THIS TYPE OF VISIBILITY ON THIS VOR-A WAS A BIT EXCESSIVE. IT WAS LIKE A 120 DEG TURN IN CLOSE AT 150 OR SO KTS.