Emissive textures in custom namespace

Hi there! I'm not sure if this is the right place to ask for help about this but I'm trying to get emissive textures to work in my namespace.
resourcepack/assets/namespace/textures is where both my texture file and emissive texture (_e) file are.
Is my emissive.properties still supposed to be in resourcepack/assets/minecraft/optifine? Or do emissive textures just not work in custom namespaces?
I thought maybe someone here knew something about Optifine/ETF emissive textures. Any help is appreciated!
(I'm on Neoforge 1.21.1 using ETF btw)