Yes, dowsing is possible in a graveyard and sometimes the accuracy is nothing short of amazing.
To make: Take metal wire hangers and straighten them out or you can get a 20" very heavy gauge wire. Mark it 5" in and bend it at a right angle (a vice works nice for this or countertop edge). Make two of these and you now have dowsing rods.
How to use: Hold rods lightly in hands, elbows at your waist, arms bent at 90 degree angle so forearms are parallel with ground. Do not place your thumbs over the bend in the handle. Do not grip too tightly.
Finding the dead: Walk over the grave. The rods should cross. They should uncross when walking off the gravesite.
Determining age: Standing at head of the grave, take a step towards the feet end. Count your steps. If the rods cross after 1 step, it as a baby, 3-4 steps a child, 5 steps an adolescent, 6 or more steps, an adult.
Gender of the dead: Stand in the center of the grave, hold one rod over head. If it points to the head of the grave, it is a female. If it points to the feet of the deceased, it is a male.
The fun thing about dowsing practice is going to a cemetery with others and then doing this without a glance at the headstone. Don't see the age or sex of the occupant and let others watch you do it. It can have very interesting results, though I can't say why in the world it has such accuracy.