Piston ring compressor tool for air compressor rebuild?

On a reciprocating air compressor, since you can't install the pistons from the top of the cylinders because the connecting rod bolts face upward (i.e., you have to install the rod bolts, pistons and rings first and then lower the cylinders over the pistons) and therefore can't use a normal ring compressor, are you supposed to use the kind of ring compressor that they use on chainsaws?

Just wondering if I need to order one. I tried researching it but came up with nothing, and wonder if any of my FABO brethren have had this problem.