What would it take to port this to Macintosh?
I suspect that it would require some work to address specific details such as capture from the camera and generating mouse events, for instance. The rest should work as is because it is based on cross-platform libraries (wxWidgets, OpenCV) and already available compiler on Mac (gcc). BUT as I do not own a Mac it is just a guess.
I would love to have a version for the Mac, so I don't have to launch Windows on my Mac when my arms are acting up. I'm planning to get funding via a crowd-funding site, most likely indiegogo.com, then hire a programmer to create a version of eViacam for Mac.
Is this something you would be interested in incorporating into the eViacam project? The interface will have to be changed quite a bit to become more Mac-like, and it will preferably be available through the Mac App Store.
Edit: It seems Apple's DRM and their requirements for applications in the Mac App Store are incompatible with the GPL license that eViacam uses, so it will have to be distributed outside of the App Store.
If you want to add something, check the feature requests (1) and the open bugs (2). There are proposals that range from small improvements to a entirely new face tracker layer, click based on facial gestures, etc. You could pick different tasks depending on the skills of the programmer and the amount raised.
Hopefully, the interface (based on wxWidgets) should auto-magically take the Mac appearance by just recompiling.