Adding Stroke or Fill to vector graphic objects that are pulled from the library

var myArrow:ArrowMovieClip = new ArrowMovieClip();
var vectorDisplayObject:DisplayObject = stage.addChild( myArrow );

I used the code above to create an instance of an arrow graphic that I made using the line tool (the graphic is embedded in a movie clip). I now want to add different colored fills and different stroke sizes and colors using code. Is it possible to do this with pre-drawn vector graphic objects, or is it only doable if I create the arrow with code using things like lineTo and curveTo?