Adding an outer glow to a TextInput's focusRect

Any ideas how I do this?

I’ve tried creating a movieclip within the focusRect skin, and applying a focus rect to this, but this messes up the nine grid scaling.

I’ve also tried bringing in the outerglow as a png, but this causes the focus rect to scale improperly, as it uses the width and height of the focusRect including the outerglow.

Changing focusRectPadding does not seem to work equally on the width and height.

Any suggestions?