Important Notes:

Some versions of Mac OSX come bundled with an older version of python.  You may need to install Python 2.5 manually before using the exporter on Mac OSX.  You will also need a version of Blender for Mac OSX that is compiled to use Python 2.5.  You can find the Python 2.5 version of Blender on this page (look carefully, it's easy to miss).  Here are some direct links for your convenience:

Python on the Mac page (python.org) - "Python comes pre-installed on Mac OS X, but due to Apple's release cycle, it's often one or even two years old. The overwhelming recommendation of the "MacPython" community is to upgrade your Python by downloading and installing a newer version."

Python 2.5 installer for Mac OSX (Intel and PPC) direct download link (pythonmac.org)

Blender (python 2.5 version) installer for Mac OSX (PPC) direct download link (blender.org)

Blender (python 2.5 version) installer for Mac OSX (Intel) direct download link (blender.org)

With installer

Mac OSX installation instructions needed. Contact jsgreenawalt@gmail.com if you would like to contribute to this document.

Manual Installation

1. Unpack the contents of the exporter zip file into a folder of your choice. Be sure that the folder structure in the zip file is preserved, and remember where you unpacked it.
2. Open Blender, and locate the "User Preferences" window header at the very top of the Blender screen. It's the one with the "File", "Add", etc. menus; and has an icon that looks like a lowercase "i".
3. Move the mouse cursor over the bottom of the User Preferences window header.
4. Pull the header down to reveal the rest of the "User Preferences Window". The "User Scripts" folder option is labeled "Python:".
5. Within the "Python:" field, enter the path to the folder where you unpacked the exporter zip file in step 1, or use the "Browse" button to locate the folder.
6. Drag the "User Preferences" header back to the top of the Blender window.
7. From Blender's "File" Menu, choose "Save Default Settings".
8. Quit and Restart Blender.
9. Check the File->Export menu for the exporter scripts.

Help Wanted

I need some help in updating the Mac installation script for the exporter (version 0.97).  If you want to help out with it, send me an email: jsgreenawalt@gmail.com.  I can't offer any money, but I can add your name to the exporter's credits :-)

Update: Thierry Faucounau has written a new and improved mac installation script that will be included with the next beta and final 0.97 release.  Thanks Thierry!