This comment might be a few months late, but I've been able to add a control that opens an Air file from a .chm file.
You can add a shortcut (Insert < HTML Help Controls < Shortcut) to a topic in the .chm file. In the second screen of the Shortcut Wizard, specify the name of the .exe file for the Air help as the program to run when the shortcut is activated.
As far as I can tell, the Air help application must be installed in order to link to it. So the shortcut shouldn't link to the .air file but to the .exe file created after the application is installed properly.
I haven't figured out how to link to a specific topic in the Air help. There are options in the Shortcut Wizard to pass command line arguments when running the program. However, I don't know how to pass a link to a specific html file as a command line argument. Any advice?
- Maura