Would crushed prednisone power applied topically to acne help reduce swelling?

No: I have heard of this as a remedy if done with Aspirin (do not know if effective), but Prednisone is administered for acne as an injection.

Terrible idea: You'll relieve the inflammation briefly at the cost of giving the bacteria a tremendous edge. If you have access to prednisone and are going to use it off-label, why not get with a competent physician who can manage your acne scientifically? Wouldn't that make more sense? It can always be kept at bay until it self-cures.