im sure im gonna hear some poo for it but it does work and it works well. the trick is to have both valves closed while the rope is pressing against the head. i know its taking a chance of damaging the piston if all the rope lays to one side but if you twist the rope as it slides into the sparkplug hole it crates a spiral effect and lays pretty evenly on the piston. also you should be sure to do it on a cold engine to avoid warping a head or something else.  once the bolt breaks loose just turn the crank in the oposite direction and the rope pulls out just as easy as it went in. the oil is just to add weight to the rope so that it slides in easer. you could need more than 2 feet of rope in the cylander though depending on the size of the engine.

Actualy I've hear of doing that before. 

ive been told not to do it with an aluminum engine but i did on a honda civic and it worked out. took a serious amount of effort though. when it finaly gave it sounded like i broke the crank. i was told to do it only on the #1 cyl because its closest to the balancer. if you were to do it to any other piston you could easily warp or brake the crank shaft.