Single button with two different Accessibility Names depending on state?

I have a smartshape button that I am using to toggle Closed Captioning on/off - which I have working.  However, I need "CC On" when it is on - and "CC Off" when it is off.  Is this possible? I tried using two images and hiding one vs the other - but then the Keyboard focus gets all messed up.

Or even better - is there a way to customize the standard playbar text - like Audio has AudioOn/AudioOff? 

Thanks

Rachel