How have you implemented the code in WPF? There is no Main method the same way in a WPF project, so the sample code above cannot be copy-and-pasted as is.
Regarding the shaking – this is anticipated if you do not do any additional filtering of the data. The data is only lightly filtered when it comes from the EyeX Engine. You need to apply a suitable filtering for your purposes. In your case something that averages the data to make the movement of the cursor smoother. You should put your filtering algorithm where the “TODO: Filtering of gaze point data” is in the MoveMouse method in the code sample above.