on my automatic z22se in astra g i've blocked the crankshaft pulley with a big metal pice like a big screwdriver or so. and than left round the screw.
it goes better with 2 person
a few years ago, i had an omega from opel with normel gearbox but the screw of the crankshaft pulley don't want to come.
so i take a rond nut and a long pip and clamped it under subfloor of the car. and then little start the engine and direkt turn off engine.
and it goes good.