How I can?
For example Marine to Shaman

The colour changing is not that precise, it's extremely to difficult to go from one certain colour to the other. I would ask FNugget.

Not sure about marine to Shaman, but if you have black/void flame just color the texture with color you want and then invert it.

Just experiment with different colors till you find correct one.

What Teurastaja said, it worked for me once.

Color your texture shaman, then invert it.