I was in the Army in the early 70's and we had a lot of tuck engines that were "multi fuel". I don't think there is a big trick to it but the compromise is that they don't run good on anything except diesel. These were big inline sixes but a turbine will run on anything that burns. Interestingly many auto makers are currently experimenting with variable compression ratio engines that convert from Spark ignition to compression (diesel) under light load. They burn gas (mostly) and the idea is that they can have an unthrottled intake and very high CR for maximum efficiency.
