I know this is an old thread, but in case anyone here is interested, it is possible to get the physical buttons on the Nook Glowlight 4 to work on KOReader and other reading apps.
Here is a link to a post of mine where I explain how it's done. The Nook needs to be rooted for this to work.
The down side of this method is that it disables the physical buttons on the Nook stock reader. However, by using an app like Key Mapper, you can make the physical buttons simulate a touch on the screen and thus turn a page.