Xml/css

I’ve got a dynamic text box in my flash document. It loads a css file and then renders my xml with the limited styles that flash allows.

I want to add a bottom border after a specific set of tags e.g.

<tag></tag>
------------- (bottom border)

I can’t hard code it into the xml file, as it will also be rendered by user input.

Is there any actionscript that can find a specific tag and then add a new tag/image/line under each instance?

I hope this makes some sense?

Thanks for any help.