Jerry,
I was in the same quandary with my MW54 as well. I found an old propane torch regulator and valve in my junk box and modified it. I thought about the on-board tank thing for awhile and decided against it. Tony F suggested the set-up shown in the picture and it works great. Basically, I run an aileron extension from the FADEC that is accessible for the start along with the gas line from the engine which has a small quick-disconnect on it. For start, I connect the gas solenoid to the extension and attach the gas. This way you don't have to carry the weight of the tank or solenoid on the airplane.........it works great!............as long as you remember to turn the gas valve on! I bought a whole case of Coleman fuel cannisters at Costco for about $1.80 a piece...........real cheap. I think Home Depot has a Bernz-o-Matic torch for about $25.00 that has a hose on it that could be modified. I saw a plumbers torch that would be easily modified because it had all pipe thread fittings, but it costs in excess of $50.00. I hope this helps.

John