Re: Switching between Alpa/Alpha Inverted with checkbox

Not exactly- at least I do not now how to do it the way you describe, but here's an alternative:
Add a Expression Control/SliderControl to your Null layer and lock the Effect Control panel. Open your Precomp and add Effect/Channel/Invert to the layer with Alpha. Link the "Blend With Original" control with the Slider Control. Now you can control the Alpha - at 100% you will get the layers alpha and at 0% the inverted alpha.

Hope this helps.

Tudor "Ted" Jelescu
Senior VFX Artist