Here a very simple Gizmo specially design for refining hard spill on hair and clothes. Sometimes Nuke despill needs a little help. It's an emulation of the wash brush of Flame using the PSDMerge on a Color operation. I normally use it before the premultiply. 

Connect a RotoPaint to RotoPaintIn and make sure the channel Output contain an alpha. The select the color of hair or clothes and paint the desired areas. 

All credit to Quico Noizeux for his expertise in Nuke/Flame equivalences. 

Enjoy!