My method:
//global var
var game_paused:Boolean = false;
Then put this if() statement around your code (you may need to do this several times if your code is seperate blocks or locations)
if(game_paused == false){
//your code
}
for stopping animation you'll need code inside each animation that checks if the global var "game_paused" is true or not. you can prototype the movieclip class, but here's the oldschool method I use. Basically I put the preceding code inside a movieclip that I can then paste into as many animations as needed to pause everything onscreen.
if(_root.game_paused){
if(pause != true)
stop()
pause = true
}else{
if(pause == true)
play()
pause = false
}