1. download both files below
2. UNZIP the "android_audio.zip" file, put the audio file in your sdk/tools folder
3. leave the "bootanimation.zip" file zipped, put in your sdk/tools folder
4. go into adb and push both files as follows:
adb push bootanimation.zip /data/local
adb push android_audio.mp3 /data/local
If you're still having issues with the sound not working, first make sure that you are unzipping the "android_audio" file...then pushing the .mp3 contained within the zip file.
Second, if it still doesn't work, try this in adb: