Hello,
I have done something very similar few years back here in freelancer.com. Here is the url, https://www.freelancer.com/projects/ActionScript/Adobe-AIR-desktop-application-connect/ I believe this is almost the same kind of project.
I did this in Adobe Air, a cross-platform where you can run the application on Mac and Windows both. I have read, you needed this on Mac, so it should not be any problem. Even if you require a dmg file, should not be problem. Let me know if you are interested.
Regards