Hi @pzstar,
Unfortunately, with the EyeX SDK the calibration routine is not customisable to the extent that you can select the points of calibration within your screen, however, the main issue you face here is the divergence between the eye tracker position and the bottom of the screen.
If it were possible to alter you design in such a way that the area of the screen to be tracked was placed directly above the eye tracker, then it may be feasible to implement this on a larger screen only if you used the Gaze SDK which would allow custom calibration point locations.
If this kind of setup is not possible, then I would suggest you investigate using the Tobii Pro range of eye trackers which allow a full customisation of eye tracker and screen position and angle.
You can send a speculative email to their support team @ http://www.tobiipro.com/contact/contact-support/