Here is what I did.
not sure if it the best way.
since the CJ fender flares are not a perfect fit you will need one or two extra persons to hold the flare up into position.
then looks to see if it looks right
then I used a silver sharpie to mark the holes, which isn’t easy with the angle
then I used a calipers to measure the proper depth from the Edge of the fender and made a little scratch mark, a ruler or tape measure may work
then drilled the holes
painted the holes with black nail polish
you will need a 1/4” wrench to screw in the screws, screw driver won’t work, and an extra person
the rear are specific for right and left and the screw holes are unique, there should be an RH and LH embossed on the flare
good luck, it’s a pain in the, well you know