Really easy. The hornady comparator is just a little piece that attaches to one end of the caliper jaw with different standard inserts for different bullet diameters. Attach it and then re-zero your caliper (or do the math with the additional length the comparator adds).
Figure out how long your chamber is to the lands (rifling) and then add the distance you want the "jump to the lands" to be, let's say .100". So, chamber length + jump = cartridge base to ogive. Just start with the die out and make little adjustments measuring with the comparator each time until you get the die set.
The hornady OAL guage makes finding the lenghth of your chamber pretty simple, especially on a bolt gun. I usually also do the magic marker covered loosely seated bullet to double check myself.
Make sure that if the loaded round comes out longer than recommended COAL that they will still fit in the mag.
Again, is all of this really needed? I just stumbled onto doing my loads this way as I was trying to eliminate as many variable as possible from the process with a problem gun. I bought the tools so I might as well use them.
If you find a happy medium in the batch of bullets and then set your dies to that length where most are right on the recomended COAL, with some a tad long, some a tad short remember that your die is seating by hitting the bullet ogive generally anyways if you are seating a spire point bullet. Once I found that happy medium place I do not "tinker" with the die, but just roll with it realizing most of the variance in COAL is from deformed bullet tips, not different ogive lengths as much.
There are some WAY more experienced reloaders who visit this forum. I only do some standard calibers on a single stage press for hunting purposes. Hopefully someone else will weigh in so you are not forming your opinion solely on my advice.