How to use Mask slot in terrain layer as eg Ambient Occlusion texture etc?

Question

Unity

I'm trying to make a custom shader for the standard unity shader for the terrain, I want to do this in order to be able to use not only albedo and normal textures in the terrain layer, but also AO, metallic, detail, etc. textures. I would like to be explained how to do this. At the moment, I realized that this can be achieved if I use the Mask slot in the terrain layer as a slot for my own texture (AO type, metallic, etc.). The only difficulty is how to implement this logic in the shader itself?