First, download the .zip file using the button to the left.
This is NOT a Runtime zip folder. You will need to manually move the unzipped folder to a location of your choice in your Poser Runtime folder. The archive will unzip a folder called Stereo Images. Move this folder to somewhere sensible in your Python folder. Mine is in:
Don’t let Poser auto install it for you.
Next - open your Poser Python window, find a blank button and link it to the Buttons.py script in the Stereo Images folder. Name the button Stereo Rendering. You should get a window containing a button like this:
Your window will be different - this is what mine looks like.
If you click on the Stereo Rendering button, you should see a window like this:
If all is well, this is all you need to do to get this ready for use.
Alternatively, put the Stereo Images in your Runtime/Python/poserScripts/scriptsMenu folder. The scripts will be available from your Poser Scripts menu.
An older version can be found here, for those who have older versions of Poser to try.