I guess I can claim to be the northern hemisphere maintainer of View3D. There are several sources for documentation of View3D. It's a bit scattered these days as I haven't had time to pull everything I've got into one location, and what comes with E+ is a little light.

• There's a short LaTeX user manual here: manual. This provides the basics on using the program. There used to be an HTML version, getting that back up is item #1 is the list of things to do.
• More technical information on what View3D does is covered in a NIST report: NISTIR 6925

Using the program in the context of E+ requires exporting your geometry into View3D's input format, running the program, then converting the results into IDF/epJSON form. You may be able to use the Excel interface to do that, but keep in mind that you'll need to do this on a per-zone basis. Item #2 on the list of things to do is to script that up. Since E+ is starting to add scripts to do this sort of thing, if you add an issue on the E+ repo requesting View3D import/export scripts, there's a possibility that I (or someone else) can get funded to do it. Otherwise, it comes down to whether I have the free time to do it.

Item #3 on the list of things to do is to unify the 3 or 4 GitHub repos (it's a long story) into one.

Update: Here's a link to the PDF version of the manual: https://drive.google.com/open?id=1fP1ou71MKkDc0VrkDJb1ZTvEJYzDo8iu