Alstan has put some great work into making it possible to import .ies files into your Rhino models with DIVA 4.0. But sometimes there is a need to change either the graphic representation (luminous dimensions) of the light source or to change the output, wattage, etc. You can do so by editing the .ies file in a text editor and then importing that file back into Rhino through DIVA. To help out, I annotated an .ies file with the terms that each value stands for, in parentheses. See attached PDF.
Pay particular attention to the the term that controls for units - meters or feet.