Napkin skins in Flex

How easy is it to skin a Flex application? As an experiment, I tried to create something that looks like the Napkin L&F for a simple Flex app. (The idea of the Napkin L&F is to have your UI look like it was scrawled on a napkin -- which might be useful if you wanted people to get the fact that your mock-up was just a mock-up and not a fully functional app.)

The application is a slightly modified version of the DataGrid sample from the Flex 2 Component Explorer. Here are the "before" and "after" screenshots (click on the screenshot to see the app):
before:

after:

So, was it easy? I'll break it down into three separate stages. The first stage involves adding CSS styles and graphical skins to the app; the second stage involves using programmatic skins; the third stage deals with subclassing Flex framework classes in order to achieve fine-grained control of the look-and-feel.