OK, I installed everything. Adobe AIR was, as I suspected, already installed with Photoshop CS5 Extended. (Remember, this is on a Macintosh.) 

When I tried to start the export, I got what's shown in the Screen Shot:

Nothing happened, though. I tried selecting first one than the other, of "data" and of "ui." Next, I went to the File Menu, and selected "Run Python Script."  I navigated to the "PoserLuxExporter.py" script and chose it. A blank box opened and the spinning beachball commenced. Nothing. Checking the App, I got the message that Poser (2010) was not responding. I had to quit the app in order to get out of it.

I'm not giving up, though. Can anyone please help? The PoserLuxExporter is "alpha_1-12," just downloaded yesterday. The LuxRender is "_v07-Install_OSX_universal_intel," just downloaded yesterday. AdobeAIR is version 2.0.3, the current version. (The Photoshop v and the v downloaded yesterday are the same.) My Intel iMac Computer is running OS 10.6.4. It's a Core Duo Extreme, with 4 GBs Ram, and an ATI Radeon 2600 Pro graphics card with 256 MBs of Ram.

Anyway, what should I try next?