Thanks for the quick response!
A workaround I’m using right now is to have a separate WPF application that launches the calibration with the Eyex SDK, and then I launch that application from Unity.
And by the way, I would suggest that even though the calibration would affect all apps and games on the machine, it should still be possible to do. In this case, and I’m sure there are other cases like this, this machine will only run this application and nothing else. When the Tobii is used in events or installations, where the calibration would be redone for every user, I believe a custom calibration would still be preferable.