Glad to hear that you've had no problems enabling telnet.
I haven't looked very much into creating raw images for the Glo, though it's on my to-do list. The raw image format for the Kobo Touch is discussed
in this thread, but if I remember correctly, the commands from that thread don't work for creating images for the Glo.
The Kobo's boot animation is controlled by /etc/init.d/on-animator.sh, which uses /usr/local/Kobo/pickel to show images from the /etc/images/ directory.