You can use the Application.themeColor style to alter the
overall color schemes for Flex. I don't know whether you not that
helps you specifically, but it will change a majority of colors
within your Application.
Just throw the themeColor attribute into your Application tag
and it will tint certain things, like focus rectangles, red
(#FF0000). Or if you're using a CSS file, the Application style has
a themeColor property there too.