Sorry, I must have missed that comment.
No, this will most probably not work on 6.2.x since there has been quite a few changes to the do_markup()/undo_markup() functions as well as the templates for the markup.
I haven't tried it though, so I don't know exactly what changes are needed, with some luck the new additions only need to be merged (and some of the markusp in the db changed accordingly).
I do not have the time to fix this myself at the moment, but I will try to squeeze it in sometime.
