I do these manually with the engine off. You can watch each one, rotate the engine until each lifter is all the way down (on the base circle of the cam). I do these one cylinder at a time, and just rotate the engine for each one, so I can keep track.

When you're ready to adjust them on one cylinder, grab the pushrod with one hand, and move it up and down so you can feel the clearance. As you're working it up and down, tighten the rocker nut slowly until you can't feel any more free play. Once you're at that point, turn the nut one full revolution, and then leave it. That's adjusted. Then move to the adjacent rocker (again making sure it's all the way down on the base circle of the cam), and adjust that one the same way. Then move to the next cylinder, until they're all done.

There are other techniques, but this one is the least confusing and most reliable method, I've done them this way forever.