From this thread on gel-coloring backgrounds http://www.thephotoforum.com/forum/people-photography/237266-derrel-kundalini-any-others-lol.html

Selective Color> Magentas> Cyan +65 units, Magenta Minus 100 units, Yellow + 100 units, Black Minus 2 units.

Selective Color>Yellows> Cyan Minus 100 units, Magenta +97 units, Yellow Minus 37 units, Black +11