From what I recall - breakfast is served Family Style and Tonga Toast is not on the menu at O'Hana. I think you will have to go to Kona or Captn Cooks.
Breakfast is family style, and Tonga Toast is not included on the menu. I've never asked to have something added to the menu, but I've also never gotten the impression that they'd be willing do that sort of thing. Can't hurt to ask, though!