The script will actually execute if you wait several minutes.  The problem is that in the middle of the script it adds a surface and then executes many, many color commands, which causes the surface to be updated each time.  If you move the surface commands to the end of the script, it takes only several seconds to execute.  It doesn't look a lot like the image on the web page because for some reason the script labels every residue in the structure.  I have attached a script with the surface commands moved to the end.  You may or may not want to edit the script to remove the label commands.