I've also wondered what a conversion would look like. The powers described seem to be incredibly high powered- I would imagine that they should be epic prestige classes. Except that in Terry Goodkind's world they seem to skip directly from low-level to epic without going through anything in between.
The Confessor's ability might be compared to an unbreakable Dominate Person, though without the telepathic control. I think it is even stronger, though- I would say that it completely destroys the personality of the victim (unless they are truly, selflessly in love with the Confessor), but in a way that leaves the memories, base attacks and hit points. The victim then becomes completely, utterly devoted to the confessor.
To model a Mord-Sith we need more adequate rules on torture and breaking people's spirits. Maybe hold off on this until after the BoVD comes out.
Then there are the Dream-walkers....