To do horizontal I would break my loaf down into the length of bar I wanted then use this to do the horizontal cuts to that chunk. In fact I can see myself doing this next time I use a 1 quart cream container for a mold. The bars are not a nice size, about 3.5 in square, so I think I will cut about 2 to 2.5 in pcs off that and then slice them down to better size - by better I mean easier to hold. The reason I don't like that size is that they are not easy to hold.
The direction of the cutting all depends on how you set it in the cutter.