I once did this for a server. The easiest way is to switch to a mod that allows it by itself (default game does not), but on the other hand, people would lose their ranks. So the only possibility keeping ranks is to use a bot. It's like an automated admin which runs on the same machine as the server and constantly analyzes the server log. It can react to lots of different events for example kills done with the GL and can then automatically kick the corresponding player. Point 1. and 2. is not possible in the unmodded game. Point 3. is of course possible but not very comfortable.