This should be really simple. Here is the script you'll need. Your mp3s don't need to be in your library, just make sure they're in the same folder as your project.

Code:
//set up variable on first frame of project
var my_sound:Sound = new Sound();


//put on frame you wish sound to start
//change soundname to the name of your file, must have extension on there in quotes
my_sound.loadSound("soundname.mp3", false);

//script you would use on your pause button to stop the sound
on(release) {my_sound.stop();}

//script to make the audio play from where it was paused
//goes on your audio play button
on(release) {my_sound.start(my_sound.position/1000);}