Currently JavaFX provides the ability for the AT to get the focus node:
FOCUS_NODE returns Scene#focusOwner()
FOCUS_ITEM, optionallly gives a view the change to specify a focus item. For example, a TableView will returned the TableCell representing the focused table item.

But the ScreenReader also need the ability to set it.
See IRawElementProviderFragment::SetFocus (http://msdn.microsoft.com/en-us/library/windows/desktop/ee671329(v=vs.85).aspx)
In VoiceOver see VO+Cmd+F4 - https://www.apple.com/voiceover/info/guide/_1131.html
It comes in accessibilitySetValue(TRUE, NSAccessibilityFocusedAttribute)

One option it to add
AccessibleAction.REQUEST_FOCUS mapping to Node#requestFocus()
Possibly we will also need
AccessibleAttribute.FOCUS_TRAVERSABLE mapping to Node#focusTraversable()
to know when REQUEST_FOCUS can be used.

The open question is what REQUEST_FOCUS means for a 'focus item' ?
In other words, REQUEST_FOCUS sets FOCUS_NODE but can it also be used to set FOCUS_ITEM ?