Roll starting

[Tassie f100]

With the system now where the clutch has to be depressed to start the engine,is it possible to roll start a vehicle now.Does the clutch in mode only isolate the starter motor or does it immobilise the whole ign system.If it immobilises the whole system then, I guess when the clutch is engaged without the engine running then, there will be no ignition power supply so therefore no start!!