Audio Tools for Xcode 4.2 Snow Leopard

Hi there, I'm looking to start making audio units. I'm using Xcode 4.2 on Snow Leopard, however I cannot find the required audio tools for Xcode. I have found them for Mountain Lion and Lion but not Snow Leopard. I desperately do not want to change my OS and am happy with my version of Xcode. I no longer have the Snow leopard install dvd. Could someone please link me to a download.

Cheers