its possible, the solution is a virtual sound card.
just create a virtual sound card with a tool of your choice, select the mic in of the virtual sound card as your windows default sound card, and the game will use it.
then just select in teamspeak/skype/ventrillo the real soundcard mic in and you can talk to friends via teamspeak/skype/ventrillo and nobody ingame hears you.
Greetings
Tepoo
