its essentially the same principle as hatmod- mount the hat to the player. the only difference is that the hats are more complex to make, they can actually be shot off of your head, and they need to be manually colored either through code or by a file of some sort.
unfortunately, you can't wear more than one bothat because every bot you mount after the first will be visible in first person, so your view will be entirely obstructed/it will look very buggy