Its a code that you enter in the console, its called voice_loopback and they say it can let the mic work while playing with others. I havent confirmed it yet so I asked guitar to give it to his friend which might be able to confirm it, I havent received word since. Do you know how to make the mic work PKJacker, that will be really helpful.
I never had to use a code for using the mic, it's already built into the game, in audio setting I believe you can turn on mic playback (volume at which others are talking) and sending volume. Then for turning on the mic, I just push a key that I mapped in controls to start transmitting from my mic.
I personally don't like having an open mic (mic always on) since it'll transmit a lot of background noise if it isn't configured properly.