I replaced the wakeup.mp3 file with a 1 second file of silence and the boot audio is now gone. Boots just fine.
I realize this is a crude method of removing it, but it was also damn easy.
Boot time is unchanged.
Here is the file:http://members.cox.net/friesen2/Commando/wakeup.mp3
Right click the link from your browser and "Save Target as" on your PC. Then you can move it to SD and use a file manager to replace the existing file. I renamed the old file as "wakeup.3pm".