Once in a while you want to be able to have an object carry out actions on a frame interval. This is simple to accomplish when you’re working with a DisplayObject, because you can just subscribe to its ENTER_FRAME event directly, but there are times when you need this functionality in a non-display object without passing around a reference to a movieclip. In some cases, you can get by with using a Timer or interval, but this is often not ideal because you have no guarantee how often the event will fire in a single frame (a timer can fire multiple times, or not at all depending on how it synchs up with a frame cycle).
Turns out the solution is ridiculously simple: Just create a flash.display.Shape instance in your object, and subscribe to its ENTER_FRAME event. DisplayObjects do not have to be on the stage to generate enterFrame events.