You don't seem to understand what a model override does. It's just a client mod that is placed inside the .bsp. So basicaly you have to make a client mod that replaces one of the bosses and then just pak it into the map. This can include models, textures and sounds. Egan jokingly did that in a 72h map. All spies looked a little flowery.I've been trying to do what Crash said, but the problem is that I'd need to create a brand new entity specifically for the boss (even if I'm just changing the model), and that's something I can't pack in a BSP, therefore, can't add it to my submission. The only option is wait for Valve to create an entity for that. Still, it would take time.