All the gen 8 Daz characters do this with their make up so far (V8, O8, etc.), the image with the make up is a PNG with a alpha channel, so you can use the RGBA image node to get the alpha to use as a mask for a Mix Texture node. I've attached examples of how to set it up in the NGE.
- Node layout example.
- Node layout with textures applied.
As an added bonus, you can mix and match the make up textures you put in the RGBA node and the RGB node, not all combinations work, but a lot of the time an alpha channel of one make up image will work with the colour channels of another make up image, just try them out and you can get a few extra styles.
For me this works much better than an Add Texture node, as it doesn't mix the 2 images together in a uniform way. There's probably a better way of doing it, but it's the best way I've worked out so far that works.
In theory this method can be used instead of the L.I.E. and you can even layer it up to a certain extent, so I generally do this now rather than using L.I.E., as it's faster and you don't have the problem of using L.I.E. temp files and them changing when you reload a scene (I'm sure there's some more complicated uses of the L.I.E. where this wont work or would just be to much of a pain to set up).
- Multilayer example.