fronts maybe. rears no way. first pic in linked thread is of 275 tire (ie, 10 mm/0.5" narrow than yours) on 10" wheel (ie, 24mm/1" narrower than yours) with ET34 offset (ie, 24 mm/1" further inboard than yours). so, take that pic, stick the wheel out an additional 1", than make it 1/2" wider than that.
http://986forum.com/forums/boxster-general-discussions/65583-wheel-fitment-question.html