Changing special regions on a texture

I don't know yet, where i have to put this here, because i don't get a starting point, on how to do this.
I don't know, if i would write a shader for this (what i from now have never done before, but hopefully will recently learn), or if i would approach it another way.
I, for now, know, how to use the emissive map, that i can turn on and off the systems visually, as you can see here:

Now - this is a complete mesh - the console - i have separated buttons and switches, so i can use them in VR, but i also want to have visual feedback from that small little lamps.
They have at least three states (Off, Green, Red), maybe more.
The emission map is made of a psd file with 4 layers in it, one for the lights.
I would love to learn, on how to manipulate special circle sized regions in this layer, or find a solution, that can do, what i want to do.

Any advices in here, on how to do this ?

 

If i am wrong here and should ask somewhere else, please advice!

 

So this is, what you do, okay:
https://docs.unity3d.com/ScriptReference/Texture2D.SetPixel.html
Not to forget about this here:
https://forum.unity.com/threads/setpixels-unsupported-texture-format.150028/

Still work left, but i now know again, what to do and search for !

 

You could apply a different material to lamps and control it's color separately from everything else. No texture editing required.

 

Thank you for answering !

The easiest and efficient way to do this obviously not is to write onto the texture.
It is a little bit of work, but i just put some planes with a white bulb presentation texture on top of the positions of these lights.
Next i also erased the lights out of the objects emission map, to get rid of the original lighting of that button.
Having that set up, i return to just playing with the materials emissive color, which is obviously way faster than accessing the texture and painting on it.

I just thought it the wrong way up ...

Here's the current result !