Huh! I wonder what happened to it.
I know that in OS9, you could user your installer disks to selectively install only certain components. I have never tried it with OSX, but if you have your disks handy you could try it.
Failing that, you could ask someone to just email it to you. I wouldn't expect Apple to object; it's not as if Installer.app on its own is much good if you don't already have the rest of OSX...