I'd answer "with a crowbar". I used to work in a railway museum and when we didn't have an engine in steam we'd do our shunting with crowbars. The technique is to get a 6 foot long bar with a bent end. Wedge the point of the bent end between the tread and rail, so the "elbow" is resting an inch or two behind the wheel and the bar is up at a 45 degree angle, so forming a lever with a lot of mechanical advantage. Put all your weight on the bar. Eventually the car will start moving. As the car moves, release the bar, slide it forward and repeat. Eventually the car will be moving fast enough that you just run along beside it, sliding the bar forward and jacking up and down with your hands. One person can move a typical car on the flat, but if that's not enough, a person with bar on each wheel will get most things moving.
Always have someone on the handbrake, as you will kill yourself if you try to stop the car with the bar!