Sorry, my mistake. I read your question wrongly the first time :/
I'm not sure if this can be done easily, or if it has been done. However look here -
http://www.binary-people.com/phpbb/viewtopic.php?t=123
It's microphone input, but it might be possible to adapt it for Line-In input. Try emailing the author.
I'm not sure if this can be done easily, or if it has been done. However look here -
http://www.binary-people.com/phpbb/viewtopic.php?t=123
It's microphone input, but it might be possible to adapt it for Line-In input. Try emailing the author.