Create 'internal clock' as alternative onEnterFrame()

I am designing a couple of games in flash and i came to the conclusion that i need a more flexible solution for timing instead of onEnterFrame; An interval based system which i can pause or change the speed, independent of the frame-rate of the flash file. So some processes might be running at frame-rate while others use the clock. One of the trickiest parts might be controlling animations with the clock, but this would allow to make a real slowmotion effect… Since i really have to brush up my skills, i have some problems/questions;

[]what technique would be most usefull for this? thinking of an interval and 'addlistener’s type of thing. Is this heavy on performance?
]Not sure if the animation part would work.
[*]Do You guys think it could be a usefull function? is there another way?

Ps. I posted this here, because to me this is more about the technique than its application (the game).