I modified the ATT Animation and inverted all the colors so it's on a black background. It looks a lot better than the stock one imo. Assuming your ATT_bootanimation is located in system/customize/resource/ATT_bootanimation.zip, you can flash the zip in recovery. I also included the original in case you want to go back to stock. Note I've only tried this on a Vivid with wcx rom, not liable if it doesn't work.
Huge thanks to homeslice976 for helping me figure out how to get it working and the flashable zip file.