If you ca find out its hWnd then you can use the setFocus API

Code:
Private Declare Function SetFocus Lib "user32" Alias "SetFocus" (ByVal hwnd As Long) As Long
but I'm not sure how Tabindex's are handled (I don't thinks it's Window's reponsibility to do the tapping, I think it's the programs, which would make it very hard)

but you could try setting the focus to the parent window of all the controls, that will probably get you to the first item in the taborder.