I don't know of a software solution for this, but I have used a line in for that. Just run a stereo line out cable from the speaker jack to the line-in jack and you're all set. I use a splitter so I can hear what's going on too. Works VERY well. You may have to hunt one down that has male connectors on both ends. Radio Shcak should have one for < $5.
Change the world. Of one person. Today.
If your equation requires either a complex combination of variables to get the desired result OR you can't seem to get the result regardless of the variables....it ain't your variables, it's your constant.