CS4 coloring

[Eireann]

I could SWEAR that I found a technique online that allows you to color one portion of a photo simply by clicking on it. I'm speaking, here, of the fun (usually) process of transforming a color photo to black-and-white, then coloring in one part of it, or more than one part.

Am I mistaken? Do you really have to use the brush each time? This is weird.

[Chromatix]

Some of the selection tools are quite clever - perhaps using one of those, and filling it with "punch through the filter" magic would work?