You just unscrew the 4 outermost screws on the barrel, lift up the mount half an inch and rotate it by 90 degrees. It needs to be rotated so both shift and tilt nobs end up on one side, and both lock screws and up on the opposite side. Then screw the mount back in.
The resulting orientation makes more sense for landscapes. I can now tilt the focus plane forward to achieve sharpness from near to far, and in addition shift the lens up and down so the horizon does not end up in the dead center.
The cable ribbon is long enough, so no extra parts are needed. With the 45 PCE and 85 PCE, a longer ribbon is needed which Nikon does not sell, so these lenses require a trip to Nikon. In any case, for anybody attempting this, use a high quality screw driver with the correct fit, so not to strip a screw. They are pretty tight.
As a side note, the 24 PCE looks to give great results on the D800. The large image circle sure helps with superb sharpness down into the extreme corners, even on the 36MP sensor.