Armor:
First convert to LAB. Then open curves adjustment layer The A channel covers green/magenta. The B channel covers blue/yellow. Negative numbers are cool. Positive numbers are warm. Zero is neutral.
For this, all I did was move the endpoints in a bunch - to like -70 and 70. The line stays completely straight, and it still intersects 0,0. This overdid the change, so I dialed back the opacity to taste, I think somewhere around 70%.
For an intro to LAB, I recommend looking at the first 5 chapters of The Canyon Conundrum by Dan Margulis. It's a book devoted entirely to LAB, and its really good. Or you could look
here for some very good summaries of what is covered.
Hope this helps.
Duffy