Flash MX 2004.
library.editItem([namePath])
namePath A string that specifies the name of the item. If the item is in a folder, you can specify its name and path using slash notation. If namePath is not specified, the single selected library item opens in Edit mode. If none or more than one item in the library is currently selected, the first scene in the main timeline appears for editing. This parameter is optional.
A Boolean value: true if the specified item exists and can be edited; false otherwise.
Method; opens the currently selected or specified item in Edit mode.
The following example opens the item circle in the test folder of the library for editing:
fl.getDocumentDOM().library.editItem("test/circle");