Native Instruments installers write files into the following directories (the ~ symbol means your user home directory)
- MacintoshHD/Applications (unless otherwise specified at installation time)
- MacintoshHD/Library/Preferences
- MacintoshHD/Users/~/Library/Preferences
- MacintoshHD/Library/Audio/Plug-ins/ VST
- MacintoshHD/Library/Audio/Plug-ins/Components
- MacintoshHD/Library/Application Support/Digidesign/Plug-ins