Japanese users have been developing a hack called "kobo cfw," one of which it modifies is the page progression direction of cbz file. It seems that the latest firmware it supports is 3.1.1, since the version was the latest one for Japanese users until this month.
an example
On the other hand, a program called
rckepub does the cbz -> right-to-left kepub convertion quite easily.
(I think both resources are in Japanese only)