FLT 1206 WAS ON FINAL FOR A CAT II ILS RWY 2L APCH. THE LAST RPRTD RVR PRIOR TO LANDING WAS 700 FT, & 1200 FT RVR WAS RPRTD AS THE FLT CROSSED THE OUTER MARKER. MINIMUMS FOR THE APCH WERE 1200 FT RVR. ON SHORT FINAL, THE CAPT SAW APCH LIGHTS & DISCONNECTED THE AUTOPILOT AS THE ACFT DSCNDD BELOW 200 FT AGL. THE ACFT TOUCHED DOWN 408 FT SHORT OF THE RWY THRESHOLD, DAMAGING THE APCH LIGHTING SYS & THE ACFT. DFDR READOUT REVEALED THE ACFT RATE OF DSCNT INCREASED FROM 720 FPM TO 1400 FPM AFTER THE AUTOPILOT WAS DISCONNECTED, WHILE AIRSPEED REMAINED CONSTANT. INSPN OF THE ACFT NAV EQUIP & ARPT NAV AIDS REVEALED NO EVIDENCE OF MALFUNCTION. ALTHOUGH THE CAPT STATED THAT HE HAD THE APCH LIGHTS VISUALLY, HE WAS UNAWARE THE ACFT HAD LANDED SHORT. THE FLT ENGINEER STATED HE FELT THE ACFT HAD INDEED LANDED SHORT. THE CAPT DISCONNECTED THE AUTOPILOT AT ABOUT 200 FEET AGL, ALTHOUGH COMPANY PROCEDURES REQUIRED USE OF THE AUTOPILOT DOWN TO DECISION HEIGHT (100 FT AGL).