I've never tried to toilet train Fushi, mostly because he usually goes outside if he can, so haven't had the motivation.
However, one day it was storming outside really hard, and he decided entirely on his own to use the toilet so that he wouldn't have to go outside!!
He did it maybe 2-3 times over a couple days, until the rain stopped, and then he went back to using the great outdoors.
Unfortunately, he forgot about it, and the next time he was confined to indoors, he went back to the litter box.