Can't- actually, nobody has yet. It dosn't mean it won't happen, and be a pretty cool hack. Early versions of OSX allowed for startup sound to be added via a third-party program. I currently just run an Apple script in the background, using System Prefs-->Accounts->Startup to get it going.
That sound is built into the ROM. You cannot change the startup chime for any Mac, you've never been able to change the chime on any Mac in history.
Sorry.
You used to be able to add a startup sound in Classic, by adding a system 7 sound file to the extensions folder or system folder. But those days are gone now.
Rather than posting a script, just use the AppleScript program to record you lanuching Quicktime and playing a sound. I use a QT movie that masks all of the other programs I use at launch. I think it's pretty cool.
Rather than posting a script, just use the AppleScript program to record you lanuching Quicktime and playing a sound. I use a QT movie that masks all of the other programs I use at launch. I think it's pretty cool.