During a night, ILS approach, the plane struck a powerline about two miles short of the runway after the pilot was provided a low altitude alert. The left engine lost power and was feathered. The pilot feared possible gear damage and left it extended. Unable to maintain altitude, the plane crashed before reaching the runway. The pilot reported ice accumulating on his windshield during the descent, but stated he could see quite well through the left quarter. He stated he was flying the approach with a glide slope indication of one dot high when he leveled off with an altitude indication of about 800 ft MSL. Before crashing, the pilot replied to an ATC query that he was in contact with the ground, had the runway in sight, had ice on his windshield, and his glideslope was not working. A check of the glide slope receiver revealed it was inoperative with a one dot high indication. The altimeters were checked and showed only a 70 ft difference. Elevation of the crash site was 596 ft MSL.