How to add these to an already modified mask:

Programs needed: Any that let you modify channels, I use photoshop.

Before starting: Acquire a file for the GREEN channel and a file for the BLUE channel for whatever MASK file you are using. For scale-shimmer, you will not need to modify the red channel.
You will also want the GREEN channel and the BLUE channel from any scale, tattoo, and makeup/blush mods

Layer order for both the GREEN channel file and the BLUE channel file:
TOP layer: Scales or any opaque decora
Middle: TRANSPARENTS FROM THIS MOD
Second to last: Transparents from tattoos | makeup/blush mods*
BOTTOM layer: default bibo / default bibo-uv based mask that you use

*I personally don't recommend using a shimmer AND the scale-shimmer from this mod itself because I think it'll likely turn out too intense/messy, but you can try if you want.

Once your layers are set up, you will from here on out focus and edit only the TRANSPARENTS FROM THIS MOD ("Middle" for sakes of this guide) layer.

1. Set the middle layer's effect to soft light (overlay or multiply could also be used if desired)
2. Select every layer
3. Merge all
4. Copy the final combined image

5. Open the file that you used for the BOTTOM layer OR open the file for the mask that you are currently using, either works.
6. PASTE the final combined image from step #4 into the matching channel (so the GREEN channel file goes into the mask's GREEN channel)
7. Save the image.
8. Follow Reni's guide for adding loose files to penumbra from here on out: https://reniguide.carrd.co/#loosefiles

Note: I do not claim for this to be the most effective or best way to go about putting the files together, this is just how I do it.

ALTERNATE OPTION:

!!IMPORTANT!!
This only works for photoshop to my knowledge, sorry.

Before starting: 
Acquire the GREEN channel and the BLUE channel from any scale, tattoo, and makeup/blush mods

Open the shimmer-scale psd

1. Add the green channel from your mod to the green channel group's folder. (overlay or multiply could also be used if desired)
2. Right click the folder labeled GREEN CHANNEL
3. Select Merge Group
4. Copy the final combined image

5. Open the file that you used for the BOTTOM layer OR open the file for the mask that you are currently using, either works.
6. PASTE the final combined image from step #4 into the matching channel (so the GREEN channel file goes into the mask's GREEN channel)

Repeat for the BLUE channel.

7. Save the image.
8. Follow Reni's guide for adding loose files to penumbra from here on out: https://reniguide.carrd.co/#loosefiles