For recruitment rewards you can get Max lumifiber, I've never seen it used however, I would assume you turn it on and off with the same keybind that turns laser sites and flash lights on and off.
Let me clear up a couple of bits here I have the Lumi-fibre and use it constantly: You can't its on all the time, get prepped for bullet magnet time. Its not a camo .. or an additional cosmetic slot, its an Armour, so if you have it on, no other armour can be equiped, or you dont get lumifibre This is more likely .... with any camo (Currently) it blocks some of the lumifibre lights.