rampancy: As I suspected, it is indeed the DOS version run in a Boxer-based wrapper. (The last time I played this game, I rolled my own Boxer wrapper after extracting the data files in the installer in Wineskin.)
Here's how you can get to the configuration file (for the purposes of this discussion, I'll assume you installed the .app in /Applications):
Control-click on the .app, and choose "Show Package Contents".
Navigate to: Contents/Resources/game
Within the "game" folder you should see another .app, named "Star Wars X-Wing SE". Control-click on *that* .app, and again, choose "Show Package Contents".
Navigate to: Contents/Resources
Within this folder is a file called "Star Wars™- X-Wing Special Edition.boxer". Control-click on this file, and again, choose "Show Package Contents".
What you will immediately see is four files; one of them is called "DOSBox Preferences.conf". This is the .conf file which has the DOSBox settings used by Boxer. Open it up in any text editor (my weapon of choice is Bare Bones Software's TextWrangler, which is free on the MAS).
Add the following entry (I like to put it after the [dos] entry, for neatness' sake:
[joystick]
joysticktype=auto
timed=false
autofire=false
swap34=false
buttonwrap=false
You may want to play around with the joystick parameter; there are more details
here, on the DOSBOX online manual. In terms of configuring buttons, us Mac users are sadly SOL;
Alun Bestor has sadly decided not to support DOSBox's built-in keyboard and controller mapper for implementation reasons.
One solution around this, as mentioned in the linked thread above, is to take the Windows DOS installer for X-Wing, and install that into your own DOSBox install with either DBGL or Dapplegrey as your DOSBox front end.
It worked! thanks so much! Only issue now is that the sound turns off occasionally, but at least I can play!