First, you make sure you have Bluetooth enabled on your S60 phone, start ExtGPS and accept both security dialogs (for positioning and Bluetooth connectivity).

Now, open Bluetooth devices from System Preferences. If you have not yet connected your phone to OSX, go through Set Up New Device wizard first.

Next, open Devices tab, you should see Symarctic ExtGPS in the Device Services list:



Click on Edit Serial Port to create new OS X serial port connecting to ExtGPS application.



After clicking Apply button, the setup is complete. Just start your GPS application and select Symarctic ExtGPS serial port.