According to ESRI:
Of these two widgets (LiveMaps and LiveLayers), only the LiveMaps widget supports scale dependencies in the Flex Sample Viewer. How the code is written in the Viewer for the LiveLayer widget is this: The widget connects to the layer, gets all the features that match the query set up in the livelayer XML config file, and then renders them as a graphics layer in the flex viewer. The graphics layer is not set up in the Viewer to deal with the scale dependencies, thus that information is lost in the translation.
It looks like this can be done though, but you will need to write some code to do it.
Hope this helps.
