I carry my CZ 75B in Condition 2, with the hammer lowered to the half-cock position.
I lower the hammer by hooking my strong side thumb over the top of the hammer, with the end of my thumb between the hammer and the rear of the slide. I pull the trigger and carefully lower the hammer until my thumb touches the rear of the slide, then I release the trigger, which activates the firing pin black, and lower the hammer the rest of the way into the half-cock notch.
This is a very similar technique to how you handle a traditional action single action revolver if you carry it with the hammer down on an empty chamber and then cock it in preparation to taking a shot. If you then decide to NOT take the shot and wish to lower the hammer to allow for re-holstering, you control the hammer with your thumb while pulling the trigger, lower the hammer past half-cock until you feel the bolt leg slide past the hammer cam, then release the trigger and continue to lower the hammer to the safety notch. Then you draw the hammer back to half cock, rotate the cylinder through four clicks, cock the hammer again and lower it all the way while holding the trigger, which (if you did it correctly), lets you lower it down on the empty chamber again.