Steven,
There is no way to do this in KENO3D. If you're running SCALE 6.2.x, you CAN specify the origin of a 2D slice in Fulcrum visualization. The origin is provided in the lower right hand corner of the window, and you can click on the field and provide the (X, Y, Z) coordinates for the desired origin.
B.J. Marshall
Senior R&D Staff
Reactor and Nuclear Systems Division, ORNL