I just found this great piece of information about resizing Flash Catalyst components with custom skins on the Adobe Technotes.
• Resizing and modifying wireframe components
• Resizing components with custom skins
• Resizing a single instance of a component with a custom skin
• Scaling and resizing components generated by Flash Catalyst using Flash Builder
• Scaling paths from Flash Catalyst in Flash Builder
• Creating “liquid layouts”, or making a Flash Catalyst application scale
Q: When I’m working in Flash Catalyst, why can’t I resize and scale my components with custom skins in the same way that I resize and scale my wireframe components? For example, after I edited the appearance of a wireframe button (I added a custom 5-pixel stroke), my button no longer grows/shrinks automatically to adjust to the amount of text I enter in its label.
A: Components with custom skins can be resized/scaled, using a slightly different method than wireframe components-- more on that below. But first, a little more info on wireframe components.