Flash MX 2004.
timeline.addMotionGuide()
None.
An integer that represents the zero-based index of the newly added guide layer. If the current layer type is not of type "Normal", Animate returns -1.
Method; adds a motion guide layer above the current layer and attaches the current layer to the newly added guide layer, converting the current layer to a layer of type "Guided". This method functions only on a layer of type "Normal". It has no effect on a layer whose type is "Folder", "Mask", "Masked", "Guide", or "Guided".
The following example adds a motion guide layer above the current layer, and converts the current layer to Guided:
fl.getDocumentDOM().getTimeline().addMotionGuide();