This is a really neat program that I have had for some time but have not used it for sometime. I have it installed and really enjoy using it. It has many features like feeding and providing beverages to the passengers to mention a few, and a few mean many more options on how you flight went, penitlties for not doing certian stuff and many many more. One thing it has that I have been playing with is music for boarding and deboarding. These music files can be changed with any thing you like. The only thing you need to do is convert the music from a MP4 or MP3 format. And to that I have found a free program to do that for you.
http://www.nch.com.au/switch/mp3.html its free and very easy to use.
FSPassengers can be found here at http://www.fspassengers.com/
this might be old for some, but I thought I would still through it out there.
The folder can be found in your root FS folder/fspasserngers/sound/crewpack.
Hope you find this useful!!