It might work without root. Just open up the .apk (from a system dump somewhere), and edit the .png's to be transparent. Then repack the .apk, and try installing it with Astro. I doubt it will work, being that it's a system app... but hey, give it a shot.
Is the one on your screenshot from a metamorph theme? If it is, link me to it, and if I have any time soon I will see about theming the one for the Nexus (not the Dream port) with the same .png's, and upload it here.