You can use the Copy With Property Links command to create such a link using expressions.
Is that available in CS6 or only CC?
The convenient way is new in After Effects CC. You can connect properties manually with expressions in previous versions.
You cannot tie an expression controller to a mask path, but you can tie one to a scale property.
An easier way to animate things like blinking eyes is to set keyframes for the various positions of the eyelids just one frame apart then pre-compose and enable time remapping, then add an expression controller for each eye lid and animate the expression controller by typing in 1 for open and 2 for closed. Here's an example using only a 2 frame pre-comp and shape layers for the eyes and just two positions, open and closed. I modified the expression controlling time remapping by multiplying the slider value by the comp's frame duration. This lets you simply type in 0 of open and 1 for closed to the expression controller and, because of the magic of time remapping, you'll get all eyelid positions from just two keyframes.
Here's a sample CC comp for you to look at:Dropbox - animatedEye_CC.aep
(note: Drop box will add a .txt extension to the file unless you use save as from the link. If it does, just remove the .txt and the project will open just fine)