I believe the manual start box from AMT has provisions for the propane, gas, and an internal battery for starting. It also can use the umbilical cord that the ASU uses. You just need the female end in the plane and the male end is connected to the start box. You can even add the EDT unit to use with the start box.
The original electric start system AMT designed used an electric starter motor on the engine controlled by a modified ASU. The ASU was connected to a 12 volt power source and propane supply. The electric supply and propane was sent to the engine via the umbilical cord. The start sequence was handled by the ASU. The neat part about it was the fact that all the solenoid valves, propane supply, and electronics were out of the plane, not taking up room, adding additional wiring or tubing headaches, and not adding onboard weight.
Operation was simply a matter of connecting the umbilical cord and flipping the switch on your transmitter. The engine went through the start cycle and you disconnected the cord. After landing, you reconnected the umbilical and the engine would go through a complete shut down cycle, including cool down, after switching at the transmitter. When the cycle was complete, you just disconnected the umbilical. Since the ASU operated off a seperate 12 volt source, you had plenty of power for the start and cool down without using any power from the ECU battery on board the plane. It was one of the most impressive designs I had witnessed. About the only feature it did not incorporate was a built in ECU battery charger. The odd part about this system was that it was shown at the first or second Florida Jets event approximately two years before any other electric start system was offered.
I am sure the guys at AMT can give you all the information you need.