I'm intrigued by a program called "vEmotion" which works with Skype
(and other VOIP programs). It's able to play sound files through
Skype's stream for the remote user to hear.

I'd like to learn how to do this, but I'm not too sure where to begin.
Playing the media files (locally) is not a problem. What I'm not sure
about is how to hook into Skype's output stream to the remote user.

I thought one "universal" way to do something like this would be to
send the audio data to the mic-input device in such a way that Windows
would think it was incoming data from the mic. I'm not even sure if
that's possible.

Any help on where I could begin would be much appreciated.