There is a FGx with some fixes for database functionality now to download. This version should work now out of the box when you follow installation instructions:
REQUIREMENTS: OSX >= 10.5 on intel-based Mac
INSTALLATION: Unzip the downloaded file and move FGx to Application folder, start FGx with doubleclick
FIRST STARTUP/CONFIGURATION: For database settings use "QSQLITE", on paths tab set paths to "Use default paths" (this will point to built-in FlightGear binaries and fgdata, a more or less recent snapshot). For choosing aircraft/airport you have to click once on "Import" buttons generate available aircraft/airport lists.
KNOWN: FGCom voice communication does not work, when it is not installed separately on your system (there is a fgcom osx installer here)
Thanks again for testing, gral
INSTALL ADDITIONAL AIRCRAFTS: Right click on "fgx-2.3.0rc3" -> open package -> open "Contents/Resources/fgx-fgdata" and move unzipped additional aircrafts into Aircrafts folder. Restart FGx and import aircraft list again -> new aircrafts will be available.
DOWNLOAD SCENERY: Check [x] "Download scenery via Terrasync" on core settings tab. Don’t forget to set path to your terrasync directory! In case you use a new and empty Terrasync directory start FlightGear and wait 5-10 minutes (until all airportfiles are downloaded). Restart FGx and "Import" airports again, you will get a list of more than 15000 airports and this will take some time.