actually there is a way, sine l4d2 runs off the kinda the same engine css does. lol its time for you guy come together with the eventscript team. i recently had to added this to our css pub. so i did researched on google and came across a hacking forums talking about hack and crashing other ppls server and what the server owners have on the server for it to actually work. and right the link below is the only one that stops them for doing it with rcon locker installed also. they have a esdead beta when l4d2 got released but there hasn't been any update to it so i'm going to give it a try and see if it will work.
http://addons.eventscripts.com/addons/view/servsecurity
yea no go eventscripts wouldn't load on the server.

dam!!!!!!!!!