Custom Boot Screen Image
Prepare a .JPG image of your Custom Boot Screen (recommended: resolution 1280x960, file size up to 80 kB).
Rename file to STARTUP.JPG and save it to the root of the SD card.
Now just insert the SD card boot your googles and marvel at your custom boot logo!
(Pro tip: that 80kb limit is not set in stone managed a couple with trial and error at 100kb.. good luck)