This is possible, however as it was pointed out most networks already have taken a strong stance AGAINST this kind of behavior as it serves no beneficial use whatsoever. That's why some major networks have crippled /who (which is what you can use for filtering hosts). If you're having an issue with a small network, I suggest contacting the admin. If that goes no where, change networks. The only thing you can do is flood the user since this small network obviously uses hostmasking, and that won't get you anywhere.

As this leads to IRC war scripting, this is no longer a viable topic to discuss on these forums.