- Open the zip file and extract /system/bin/bootanimation and /system/media/bootanimation.zip.
- Put bootanimation into /system/bin/ and bootanimation.zip into /system/media.
- CHMOD /system/bin/bootanimation to 0755 (-rwxr-xr-x).
- Reboot and enjoy!
I whipped up a CWM/TWRP flashable ZIP to enable the Android L boot animation. Flash tmo_kk_androidl_bootanim_n900t.zip if you want to leave your current boot sounds, and flash tmo_kk_androidl_bootanim_n900t_nosound.zip if you want the script to rename the PowerOn.ogg and PowerOff.ogg.
This script will backup the original /system/bin/bootanimation so you can easily revert the changes.
I tested this on my N900T running EffortLess ROM Rev 6 (NF1) w/ Aurora Kernel, though I'm fairly sure it would work on other ROMs/variations.
EDIT I updated the zip files to the latest version that do not have the error issues. Thanks to @Dan-SRi for pointing out the problem!