[flexcomponents] graphical skinning - css - swc

[Muzak]

I'm working on a custom component (VideoControl, AS3) that extends HBox.
The HBox will have a default backgroundImage (symbol in swf).

When I use the VideoControl in an mxml file I can define the backgroundImage 
through css

VideoControl {
    backgroundImage: Embed(source="/videocontrol_Assets.swf", 
symbol="ControlBackground");
}

This works fine.

Question is, when I compile the VideoControl.as (+css +assets.swf) to swc, how 
do I tell the VideoControl to "pick up" the 
backgroundImage?
Should I create a seperate Skin class for the backgroundImage?
If so, how do I then prevent this from colliding with the backgroundImage style 
of the HBox?

regards,
Muzak