Emissive texture on blocks

So I'm trying to create a new block that spawns in the pale garden, and it's supposed to bloom at night like the eyeblossoms and glow in the dark like they do. I've checked the option for "emissive rendering" in the block properties, but it isn't rendering how I want it to. I have an extra texture to map where the glow should be, but you can only apply those textures to living entities for some reason. How did Mojang achieve this effect, and can I somehow do it too? I've already gotten it to bloom at the right time and now all I need is the emissive rendering.