Replace Glyphicons-Halflings with Glyphicons-Regular fonts

I am struggling to understand how to incorporate Glyphicons Pro fonts into the Sage starter theme. Unfortunately, the Glyphicons Pro icons is not available as a bower package and therefore the Font Awesome discussion on the forums does not help out in my case.

I have the following assets from Glyphicons. Font files and two CSS files.

I have placed the font files in the assets/fonts directory and gulp watch has copied them over to dist/fonts folder.

What to do with the CSS files and what is the best way to import them into the main.css file?

Any help or pointers is much appreciated.