About 35 miles southeast of the destination airport, the pilot received the local weather information. The pilot requested the instrument landing system approach (ILS) to runway 31. Upon descending to the decision height, the pilot saw the runway end identifier lights and continued the approach. The pilot then saw the visual approach slope indicator (VASI) lights and the runway lights, and decided to land. The airplane touched down approximately 1,000 feet down the runway. The pilot reported that when the tires came in contact with the runway the brakes would skid, then "grab", skid, and then "grab". The pilot elected not to go around, remain on the runway and attempt to stop the airplane. The airplane traveled into the snow covered terrain off the departure end of the runway where it contacted an ILS antenna pylon, which resulted in substantial damage to the left wing spar. The pilot reported that the downsloping runway was ice covered, that he landed with an approximate 8 knot tailwind, and there were no mechanical failures or malfunctions of the airplane. He also stated he had no prior knowledge of what the braking action on the runway would be.