Hey teak421,
I have found the best way to control a material you wish to look similar to that of ‘Unlit’ mode is to create an Unlit material and add a multiply scalar parameter and a power scalar parameter.
The multiply will serve as a way to control brightness and the power will serve as a way to control the contrast. I have created an example template which you can use to create your own master material which you can instance and tweak the parameters to achieve the desired look you are going for.
Master Skybox/Cubemap Material
In regards to the Light Particle Emitter, you want to make sure you are using a CPU particle emitter and not a GPU, or else the light module will not appear in the list of available modules.
Particle Lights
You can see where I have outlined in Red the differences between the emitter types, and the available modules for the CPU emitter type.
If you have further questions or need additional assistance please let me know.
Cheers,