First way is sending each command per 0.5 secound - "/say ." - you can do it in config_mp file (if you choose this - you cant chat while on server).
Second is change "+attack" button, create own server, wait 1 minute, not pressing MOUSE1 and play any server (you must change attack button from left mouse click to any other, for example... ALT?).
Third - edit .dll file.
I found a .dll file what send 2 massages per 10 minutes, its still shitty but better than 100 messages per minute