Huh, I thought this was about something like an automated translator for people like XSAX or something like that.
Well I am not sure if I understand you correctly, but if you would like to add custom weapons, you of course will not be able to do that during an online game nor apply any custom weapons to anyone on a standard public server.
But what you can do anytime is to have a look at the source code and start coding to implement a weapon that you think you would like to see ingame. If you succeed at that, you can then use such weapon on your local machine or even set up a server that provides this custom weapon. If you intend to develop a weapon that gets added to the official game then I'd suggest to get in touch with the developers on IRC (see the Thread
http://forums.alientrap.local/viewtopic.php?t=3807 for more info).
If you do not like coding, then the best solution would be to post your ideas about new weapons here, with some more detail about what they could do and hope for a productive discussion. (Good luck

)