Once you have a good punch, ground at a slight angle, most will come loose. However, those that are tighter than usual can require a bit of extra support, so the force of the blow isn't attenuated. For these I over-inflate the tire and wedge the wheel into a corner formed by my workbench and a concrete wall. I lean into the 3rd side firmly with my belly and use the punch. The hub moves less when struck, no problem.

BTW in the previous thread referred to by Cyqlist, I mentioned marking one notch and a nearby spoke so you can be sure the ball cup didn't end up 180 degrees from it's original orientation. The other day I repaired a friends FM (same ball cup) and forgot to do so. When we installed the rear wheel there was at least 3/16" of lateral runount. Reinstalled the ball cup and the wheel was true again. It's not a problem most of the time, but its simpler to mark them all than to have to reinstall a few.