Please put this file in the repository. I don't know, but somewhere. So it outputs a bootsplash.jpg file to wherever SeaBIOS is looking for that file.
#!/bin/sh convert -background black \ -font /usr/share/fonts/truetype/ubuntu-font-family/Ubuntu-R.ttf \ -pointsize 96 -size 320x480 \ -gravity East -fill '#2078cb' label:'Sea' \ -gravity West -fill white label:'BIOS' \ +append bootsplash.jpg