How to paint paper mache rose
If you have a dual-action airbrush and a volatile pigment like alcohol inks, you can spray the rose from a distance at low pressure with a high air-to-paint ratio.  The low pressure will keep the air jet from damaging the rose while the distance and high air-to-paint ration would allow the volatile ink to be almost dry by the time it hits.  

Experiment with this technique by trying to paint tissue paper without ripping it.

A low tech equivalent to this technique would be spray paint at double the prescribed distance with a strong tail wind or electric fan running behind you.