I had a buddy that would use my press and do them.. Main trick is to scribe them first.
I am thinking, 20 or 25 tons will do most..
He used what he called a CAN to do them, and we built a few. Basically a heavy tube with notch for the rod, and a plate to support the flywheel halves, while pressing pin out or in. More than one cylinder, it gets more involved.
Usually pressing involves shims to maintain side clearance, and assembly must be trued after pressing together. The key here is using the scribe lines, and a square to line up the bits on reassembly... one time he got it to 2 or 3 thou, just pressing it together.. very little truing on that one.