Yep, I knew this would happen. I kind of rushed out the plugin, only supporting users that install it into their user script dir. As you might know Blender looks for scripts in both default and user script directories.
Whatever, I did what I should have done straight away and put an updated version 0.51 on the website, it now supports both script dirs.
(NOTE: Don’t forget to install both scripts.)
Hmmm, as far as I can see you selected an empty object or any other object without any vertices/edges/faces. The error message means the object you selected doesn’t have any mesh data. Maybe it is a NURBS object (‘surface’) ? The script only works with polygon or subdivision (‘meshes’).
To be on the save side, try this: select exactly one object, press Tab to go into EditMode and then start the script. If it’s a polygon object, there will be no error. (at least not this error, I know the script ain’t perfect yet…)