Apparently with the newest Realtek HD audio manager you can do "Connector Retasking", which is what you're looking for.
I think you can download it here:
http://www.realtek.com/downloads/downloadsCheck.aspx?langid=1&pfid=24&level=4&conn=3&downtypeid=3
and additional information you can find here:
http://www.vistax64.com/sound-audio/64250-latest-realtek-hd-audio-driver-version-41.html
and here:
http://www.techspot.com/vb/topic166497.html
Grtz!
I don't think it can be done. Audio out (speakers) is just that, an output. Mic is an input. I don't think the ports can be reversed. But someone else may know more about it.
Is there any reason why you want to do that?