I have implemented Cage o’ Death as a SourceMod plugin. That page has all the information that you need.
By the way, this plugin is very much in alpha/beta. I haven’t gotten to test it much, but I have been through a few games with other human players on co-op mode. Have yet to try it on versus. (Although it’s not very fun on co-op because the infected won’t get you. You need to play against other humans.)
Also, there is presently no way for a survivor to cleanly choose another weapon to use. S/he has to use the give command for now. Molotovs are not supported either (it’s an interface issue), so I changed the rules to specify two pipe bombs.
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