Thanks to nodramachicks, AKSD and me of course. This Application automates the commands to change your phones boot image as described in
Section "Q" of the Guide to Modding
How to install:
It's a normal .pkg app so it's easy to install for details about this read stickies.
How to use:
-Browse your phone's memory by the default browser and open the desired gif image with BootImg.
(don't check the Always use this app.... thing)
-It will ask if you want to apply it as boot, click yes
-It will ask for reboot, click yes if you want to see the result.
LINK
Thanks to Motorolafans user starkrav for the original instructions.