Doh!!
From memory, the procedure is pretty much the same, but some folder names may be different (i.e not Igo834!). Essentially, you need to look for the folder "Branding.zip" and then drill down 'till you find a file called "Loading.BMP". This file is the splash screen pic, so you can replace it with whatever you like (as long as its size 800x480 in bmp format).
Sadly, I haven't yet been able to change the wallpaper in Primo, so if anyone else knows......
Best of luck,
Cliff