<p>Is it possible to assign a global hotkey to a specific feature in an Adobe AIR app, i.e. the app feature responds to the hotkey whether the app is active or not (it must be running of course, but only in the system tray).</p>

I don't this it's possible with Adobe AIR itself. The only method I can think of:
Install 3rd party hotkey application (like
AutoHotkey
or
HotKeyBind
)
Configure hotkey application to make
CTRL
+
ALT
+
Q
to launch
"
```
c:\programs\thvo42\coolapp.exe --hotkey q
```
"
In your AIR application, register for the
NativeApplication.invoke
event, and watch for arguments like '--hotkey q' to know that the Q hotkey was pressed, and then act accordingly.
Of course, this is kind of a hassle, maybe with some hacking you can roll it all into a single install file.