Assuming you do mean that you want to apply tracking data to a mask, heres one way you can do that:
Create a new null. Apply your tracking data to the null.
Now create a new black solid -- make it approx 25% bigger than your comp setting in both height and width. Now paste your mask to this solid. Make sure this solid layer is directly above the video layer that you want the mask to affect. Now set the video layer's track matte to "alpha matte" of the black mask solid (or depending on what you want possibly inverted alpha matte).
Now, using the pickwhip, parent the black solid to the null that has the tracking data.
(You needed to make the black solid bigger than your comp solid otherwise, as the solid moves around based on your tracking data, the edges of the solid would mess up your matte).