Sorry I didn't see this earlier, I've been busy.
Anyway, to answer your question, to create new console commands, you only really need to change the server side of the code. Meaning, as long as the server has the new .dll, things will work fine.
However, unless you add the command to the cgame, it won't show up on the autocompletion list of commands on the client side. But, that's pretty minor because even Raven didn't do that for a lot of the server commands.
If you need more help on how to do cvars, check out the Q3 tutorial on the subject at Code3Arena
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