I was able to make the KOReader cover image power off image to lock image.
Create the bmp file at /ext1/system/resources/Line/"taskmgr_lock_background_landscape.bmp following the specs of at the link a user posted (
http://cyfranek.booklikes.com/post/5...kow-pocketbook).
When I created this image I made the entire picture just the transparent color described in the blog post.
Open KoReader and point the cover image plugin to this file created.