Button Text Colour

I am creating an application in Flash CS3 for a client who has strict colour requirements. I have to display a lot of images and need a lot of buttons with different text to display images on roll over. I have created a simple movie clip with just 2 colours (on and out) and the static text label (in Black) for each button on a layer above. The problem is that on the yellow background it works fine on the roll over dark blue not too good. So the text also has to change colour.

How can I do this change without creating an individual button + text for each and every button? If I make a button with text and then edit the text for an instance it changes everything.

Can I target the text to change colour in AS?