C:\Documents and Settings\Admin\My Documents\Electronic Arts\The Sims 3\Downloads
You don't need a special program to do it. All EA downloads can be found right there. If it's non-EA custom content, you probably used the Installer Monkey, correct? If that's the case, check out:
C:\Program Files\Electronic Arts\The Sims 3\Mods
You can hand pick any content you have used for TS3, quick and easy.