I understand that Ctrl + F8 can be used to access the built-in Apple menu and Ctrl + F2 can be used to access program menus (e.g. this existing answer).
However, I have a bunch of user-installed items in the menu bar (e.g. Better Touch Tool, Caffeine, Alfred, Dropbox, etc.) and neither of the above key combinations allow access to these items.
How can I access the user-installed items in the menu bar using the keyboard?