There really isn't that much support for the mac versions is there! Which is very unfortunate. However, I found out where the mac version of Fallout GOG keeps its save files. Unfortunately however, I have been unable to use a character editor on these files as when these files are replaced, fallout recognises them as corrupt files. :(
Here is how to find the save games and save character files on Fallout 1 GOG on Mac OSX 10.8.x
1. By default, the /user/Library folder is hidden. You will need to make it visible again.
Launch Terminal, and type in
chflags nohidden ~/Library/
This will permanently reveal the /[User]/Library folder. OSX hides this so you don't accidentally screw around and break something.
2. Now, navigate to this folder.
Macintosh HD/Users/[your user account]/Library/Application Support/Boxer/Gamebox States/com.gog.fallout
Now, when you open this folder, you will see a file called Current.boxerstate. Right click on this file, and select "Open Package Contents".
Voila! Here you will find everything you need. (See attached image).
Now. IF you figure out how to edit your save files or character save files with a fallout character editor, please share here!!!!