Unable to livestream with USB headset

[cyber_etah]

I recently got the Steelseries Siberia USB Headset V2, and because I use a Mac OSX Lion (v. 10.7.2) I had to use the USB in order to connect both the mic and the headphones.

My problem now is that I can't stream the audio on livestream procaster without using Speaker's Audio, and when I use Speaker's Audio the sound is redirected to my internal microphone. I no longer hear my laptop's audio in my headset, but rather the internal audio from my laptop. And when I use built-in input, I can hear the audio in my headphones, but it is not heard in the livestream procaster.

Can anyone help me out here? I took a screenshot just to show what I have as options in my audio bar. http://i.imgur.com/O5N7b.png

Any help would be appreciated!