Where to save custom classes (so they are shared)

Hi all - I just switched from CS3 to CS4. In CS3 I had built up a big library of my custom classes and saved them in some folder (i forget which and my old hard drive is dead) within my Flash application folder so that I didn´t have to copy the library into every new project I was working on.

For the life of me I cant figure out where to put them in my new CS4 folder.

to be clear - i want to be able to import any of my custom classes like this…

import mylibrary.mycustomclass

without putting a folder “mylibrary” with a file “mycustomclass” in every project i am working on … i want to have it work like any other class native to flash.

thanks.b