I've been feminizing using aspirin for years.
I add uncoated aspirin (two aspirin per gallon, for 3 consecutive waterings) to my confirmed fems, at beginning of flowering stage. After a few weeks, they will produce a few pollen sacks filled with femmed pollen. Only draw-back is by the time the pollen sacks are finally ready to open, it's time to harvest. (but is ready to be painted onto next crop of fems)
Have never heard of 'feminizing' a male's pollen, but definatelly do not want to have that much pollen/potential pollen floating around my growspace.