On November 1, 1998, at 2001 central standard time, a Cessna 310I, N8069M, sustained substantial damage during an undershoot to runway 4 (6,701' X 150' dry/asphalt) at Rock County Airport, near Janesville, Wisconsin. The pilot said that because the nose landing gear would not extend an emergency landing was initiated. He said that during the emergency landing the engine power was reduced to zero and the landing was short of the runway. The pilot and one passenger reported no injuries, while the pilot rated passenger reported minor injuries. The personal 14 CFR Part 91 flight was operating in visual meteorological conditions. No flight plan was on file. The local flight departed at 1825. In his written statement, the owner/pilot indicated that the pre-flight was conducted in the hangar. He said he decided to pull the airplane out of the hangar by use of a tow bar, after which using an auxiliary power unit the engines were started. The pilot was in the left seat during the engine startup. After stowing the auxiliary power unit, the other passengers boarded the airplane and the airplane departed on a local flight. During the landing gear retraction a "... loud bang was heard... ." He said that when he attempted to lower the landing gear utilizing both normal and emergency landing gear extension procedures; he was unable to obtain a safe gear down indication. After making a low pass over the airport, it was determined that the nose landing gear was not extended. He said he then decided that an emergency landing would have to be conducted. He stated that during the final approach the engines were shut down, and the fuel and electrical switches were turned off. The pilot said that it then became apparent that the airplane would touch down short of the runway. At that point the pilot/passenger in the right seat took the controls and an attempt to regain power was initiated; however, the airplane impacted the terrain 750 feet short of the runway, prior to restoration of sufficient power to avoid the undershoot. After the accident the tow bar was found adjacent to the airplane in the field. A subsequent examination of the airplane revealed no pre-accident anomalies.