Quick cleanup for a dirty bird

[Farmgirl Lily]

My Buff Orpington hen named Penny is in need of some cleaning. Because of her fluffy feathers on her rear, she has, ahem, chicken guano stuck to her feathers. As it is rather built up (because she absolutely hates to be touched back there) and knowing that chickens do not enjoy water, does anyone have suggestions on a quick guano-busting cleanup that will be as little upsetting as possible? Thanks!