Take a look at
this site. It's not specific to the ebookwise, but it's compatible and it will give you some hints. (ebookwise is a ETI-2 device, just as the REB-1100 and the GEB-1150).
I forgot to add, that after making the changes to the ODF file, you have to open it in ebook Publisher and build the corresponding ebook. You'll end up with an IMP file which you'll upload with GEBLibrarian.