Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.
This isn't too hard to do.

NOTE: Always, always make a backup if you muck around inside an application bundle, just in case something goes wrong.
  1. Open the Applications folder
  2. Open the Utilities folder inside it
  3. Find the Installer program
  4. Control- (or right-) click it and choose Show Package Contents
  5. Open the Contents folder
  6. Open the Resources folder
  7. In here is the sound file you need to replace. You'll need to make sure the original sound and the one you're replacing it with are in the same format, as well as have the same name.
  8. To find which sound file is the right one, if there's more than one, just open the sound files in QuickTime Player and listen to them.
 
Installer isn't in Utilities, it's in /System/Library/CoreServices, and I can't find any sound files inside it.

I can't find the sound file anywhere. :(
 
Finally found it - took some searching.

Code:
/System/Library/Components/CoreAudio.component/Contents/Resources/SystemSounds/system/burn complete.aif
 
Cool! Thank you. I will convert this to aif and try replacing it as soon as my boss steps out. :cool:
 
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.