just put it on the kitchen table, garage work bench, etc, and put the cross hairs on something, without moving the rifle, turn the turret counter clockwise. if the crosshairs end up below your object, then counter clockwise is up, and visa versa. same for windage. not one shot has to be taken.
if the scope isn't marked, take the tip of a knife and scratch off a little bit of the black finish of the scope either on the turret or at the base of the turret on the adjustment housing, basically engraving U > or R v (usually counterclockwise) / < D or L ^ (usually clockwise) or any combo or both.
you can leave it as such or take some paint, wipe over the "engraving" with a papertowel to fill the grooves while trying to remove anything above the "engraving" (like a spackle job). when dried you can clean up any of the haze left from the paint with a Qtip and acetone.
you can add lines / numbers to the turret using the same method, and as such do the math and "convert" your optic from the generic IPHY adjustments to mil, moa, or whatever by putting the lines accordingly.
you can also put text in a word doc, shrink the text, print it, trim it, tape it to the tube or adjustment housing with clear packing tape.