Sprinkling calcium is more likely to provide an overdosage than to give your gliders the correct amount of calcium for their needs.
It is best to choose a staple recipe that contains the correct amount of calcium in the recipe so the gliders get the correct amount daily.
With the HPW diets you need to feed a wide variety of fruits and vegetables and include some of the high calcium fruits and vegetables a few times each week. Spinach and dark green vegetables, okra, broccoli, bok choi and Papaya are all higher in calcium than phosphorus. I suggest limiting very high phosphorus veggies like corn and peas to only once or twice a week.