One should use some kind of case splitting tools. Home made tools can be made that bolt to the cylinder studs and push against two crank throws with a threaded rod into a fixed nut at each location. Aluminum spacer shaped to fit the crank throws to prevent crank damage.
There are much better tools commercially available but a lot pricier.
One should also have the tools shown in the OH manual for joining the case halves back together.
The Lycoming school has a home-made slide hammer that works great for this. They welded a socket that fits the large through-studs on to a regular slide hammer. You screw it on the studs, and bang away, pulling the studs. Then remove all the case edge bolts (including the one behind the cam gear!), and the case pretty much falls apart.
Paul