How to import a PPT template (.pot) file as a Theme or Master Slides in Keynote

I was hoping that the latest Keynote (5.3) would allow me to import a Powerpoint template file as a new "Theme" for Keynote. Keynote does not recognise .pot files. Previously, using Powerpoint, I converted a .pot file to .ppt and imported it into Keynote. But then I could not find any way to create Master Slides from the imported sildes.

The notes for the latest Keynote mentioned new ways to create Themes but it seems that .pot files are still not supported.

Hopefuly there is a way to do this.