I do know about how to do this easily
Be sure to keep a back up of a default_scheme.nxmi handy
you take a scheme.nxmi and open it with a text Doc
You'll see coding that works with the color and and sprite placement
focus on the colors. you see that the colors are Hexadecimals.
Open up paint and past an image with a certain color you want to use.
use eyedropper then open up custom colors.
Next go here
HTML Color Codes and apply the RGB co-ordinance, You'll get your Hexadecimal code there, keep note of each code you want to apply.
Next when you have your scheme file open, Take the color that's already there and apply it to were it says "FROM" (Replace the default) and put the color you want to it to change to and apply it to where it says "TO", it you want to change two colors of the Lemming you do the same thing to the other piece of color change code (The default scheme comes with two for the athlete, one for highlighting and one for the zombie) if you apply this correctly save your scheme file, add it to the custom files of flexi tool and a build .nxp
Also THIS IS MY 1000th Post YAY, What do I win?