actually, no need to put the vst's in a separate folder. just let it install in the default folder, and then every DAW automaticly finfds the plugins instead of having to select the folder manually.
the default folder is: macintoshHD/library/audio/plugins/VST. the audio-units (=Components), RTAS etc are in their own folders.
off course in the default plugin-folder, you can still make your own structure with subfolders, and ableton will see these as such.