As far as I know the 'Ohana breakfast is only the family skillet ... eggs, sausage, bacon, waffles, etc. No tonga toast. It definitely isn't served with the standard breakfast and I'm not sure if you can make special requests outside of that (unless you have dietary needs).
You can get tonga toast at both Captain Cook's & Kona though. If you're stuck you could go for your 'Ohana breakfast & then pick up some take out from CC's after!
I think this is mostly YMMV, but I was able to order Tonga Toast from our server at Ohanas a couple of summers ago. Just ask nicely and see what happens. (I was charged extra btw).
Also, just my opinion, but the Tonga Toast at Kona is far superior to Captain Cook's. Not sure if it is presentation or quality of care during preparation, but I hate CC's TT.
I remember reading a few posts in the past where other DISers were able to order Tonga Toast @ Ohana for a $5 surcharge. Don't know if it is a standard practice or pure luck
You can also get the same Tonga Toast at Captain Cooks for the same price as the surcharge alone. The CS version is around $5. You just don't get the breakfast meat.