WHILE RECEIVING VECTORS FOR AN ILS APCH, THE ACFT ENCOUNTERED RIME ICING CONDITIONS. THE LEFT WINDSHIELD BEGAN ICING OVER & WOULD NOT CLEAR WHEN THE PLT ADJUSTED THE WINDSHIELD HEAT FROM NORMAL TO HIGH. SINCE THE AUTOPILOT WAS ENGAGED, HE MOVED TO THE RIGHT (COPILOT'S) SEAT. AFTER TURNING INBOUND ON THE LOCALIZER, HE DISENGAGED THE AUTOPILOT. PRIOR TO REACHING THE OUTER MARKER, HE CYCLED THE DEICE BOOTS & NOTICED THAT THE WING BOOTS CYCLED PROPERLY. WHILE ON SHORT FINAL WITH 60% FLAPS & 130 KTS, A SINK RATE DEVELOPED. THE PLT APPLIED POWER & THE SINK RATE DECREASED MOMENTARILY, THEN BEGAN INCREASING AGAIN. SUBSEQUENTLY, THE ACFT LANDED HARD ABOUT 125 FT SHORT OF THE RWY. IT THEN ROLLED ONTO THE RWY & SKIDDED OFF THE RIGHT SIDE INTO A SNOW COVERED AREA. THE ACFT RECEIVED WING & ENG DAMAGE DURING THE OCCURRENCE. A POST-ACCIDENT EXAM REVEALED THE RIGHT SIDE OF THE WINDSHIELD WAS COVERED WITH ICE & APPX 1/2 INCH OF ICE REMAINED UNBROKEN ON THE HORIZONTAL STABILIZER. THE STABILIZER DEICE BOOTS WERE CYCLED & FUNCTIONED PROPERLY.