Hi everyone, just arrived here.
I just got an Aura, that in Italy is branded by "Mondadori".
The hack worked perfectly (my firmware is 3.15).
The right size for the Aura screen is 758*1024 and i made some very simple images with photoshop, exporting them as png with 16 grays; the hack works perfectly along with the editing of affiliate.conf changing affiliate=Mondadori to affiliate=Kobo (note that change this file made my kobo begin using the cover of the book i was reading as the screensaver, so i had to remove that flag in the settings).