Program used: Adobe Photoshop CS2
Diffycult: Easy (2 STEPS!)
PSD: Yes (just ask)
Examples:
1. Selective Color
Reds
cyan -100
magenta 0
yellow +100
black 0
Neutrals
cyan +27
magenta 0
yellow +25
black 0
2. Channel Mixer
Red
red +105
green 0
blue -30
Green
red -21
green +120
blue 0
Blue
red -4
green +17
blue +100
Here we go :)
If you want, you can sharp a little.
Sorry, if there are any mistakes...