now lets let the experts have a go at this.
Nay, come on, let the armchair amateurs have a go first. (That would be me then... I've never hand-swung an engine, let alone use external machinery to start an engine.)
I'd wrap the rope around the dome maybe six times or so, obviously in the direction you want the prop to turn, and making sure that the second, third turn and so on are all over the bit of rope from the first turn so that the rope is stuck on for the first few turns by friction alone, but comes loose automatically later on. (You do NOT want the rope to stay on with the engine catching, so no knots - although first picture of a snowplough twisted around the prop would be worth something too.)
Then do the pre-engine start things as usual, including suitable priming for the climate (if there's a snowplough involved, I somehow don't think we're talking tropical climate here). At the time where you would normally engage the starter, tell the snowplough to rev it. The snowplough is of course attached to the other end of the rope, probably with a quick-release knot or a man with an axe standing by (or both), and runs sideways away from the plane, just a little forward of the prop arc, so that the rope doesn't get caught in the blades.
Most likely you'll try with about six turns or so around the hub first. Three to create enough friction so the rope doesn't slip straight away, and three to rev the engine to starting speed. If that doesn't work, gradually increase the number of turns around the hub.
It's no different from hand starting an outboard motor, really. Just a tiny bit bigger.