Quick little question: Is there a way to take the input from the onboard microphone and send it out on the earphone port? Essentially a "hearing aid" or remote microphone app?

I want to do it so I can use a 3.5MM male-male connector to connect it to the line-in jack on my desktop, when my other mics aren't available.
I did this with my last mp3 player, an iRiver H320 with Rockbox on it - It worked out great. I'm just trying to figure out how I can do it with my N900.