One more step I forgot to add is to import the blender template script.
Download the zip from here:
https://github.com/jedfrechette/sIBL_GUI_TemplatesThen in the export tab of sIBL GUI right-click in the Templates Outliner and choose 'Add Template'.
Browse to the unzipped script and accept.
It worked first time with Blender using the 'Send to Software' Loader script (Blender was running with the sIBL GUI plugin installed and enabled and the server started from the Scene tab of the Properties Window).