Chief...,
This is fairly easy to "walk" someone through, a little tougher to write. You don't shoot differently, and you don't start at your estimated POD (point on distance).
First, you need a large target like a 4X4 foot butt. A 2' square (little block type) is not really going to work very well.
You start at 5 yards. Put a small mark on the butt that you can see at all distances ( I use blue painter's masking tape but whatever you have.
Place the mark about 1/3 of the way up the butt from the bottom. Place the arrow tip on the mark and shoot. You are NOT trying to hit the mark just placing your arrow tip on it!! Discard shots that you know are not well executed!!
The arrow should hit somewhere ABOVE the mark. Write down the results: "5 yards -- 10" high" for example.
Move back to 10 yards and do it again -- use the SAME sight picture! Again write down the results: "10 yards -- 14" high. Whatever measurement you get!!
Keep doing this in 5 yard increments and writing down the results.
You MIGHT get to a place where your arrows are in danger of passing over the butt. Move the mark down. For many split finger shooters, the arrow will be hitting as much as 30" high at 30 yards, so if necessary move the mark down on the butt. Eventually, as you move back, you will see that the measurements are starting to decrease and soon you will be at or very near your point on distance.
You do not really need to worry about the point covering the mark, just keep essentially the same sight picture for each shot.
If you have written down each 5 yard result, you will have your "gaps" all the way out to your POD. The measured distance your arrow hits above the mark is the distance BELOW the bull's eye you need to hold the arrow point in order to HIT the bull's eye.
If you shoot 3 under, your gaps will be smaller and your POD will be shorter.
Work up to your POD, don't just try to start there. Also, be a precise as you can but remember that, as you point out, the arrow point is pretty big compared to a distant target. DON'T stress over this just do the best you can and you'll be surprised how accurate you can be with this system.
Arne