recolor skin tones/overlay?

So I'm trying to create colorful skin colors for who I want to be humanoid aliens in my sims 4 game. I can't figure out how to do the editing myself in a way that works, and simsvip.com/2014/09/21/the-sims-4-custom-content-95-skin-overlay-colors/ isn't working on my game (which I installed a few days ago).

Any suggestions? I have the body textures for the male, female, and child, though I don't even know if they're from sims 4 or an older game...