Don't know about EasyGaze, but when you use Gaze (the one from my Life package) the usual way to go is to disable head rotation in your animation and let Gaze control that. You might then animate the EyeTarget or even parameters of Gaze instead.
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Otherwise, you can always disable plugins via triggers. E.g. adding a Trigger track in Timeline. The question of course is how the plugin reacts to that and what happens when you reenable it.
Example using one of ReginMocap's motion captures where head rotation is controlled by Gaze and eyes by Glance. It integrates so well that Reign didn't even notice it wasn't his animation anymore when I showed it to him