[vtkusers] Volume origin,bounds, extent question

[Kall, Bruce A.]

I'm reading in a premade (raw) image volume. I know the voxel size (same 
for all dimensions) as
well as the coordinates of all 8 corners of the volume.  I'm using 
vtkImageReader.

This only seems to allow me to set the coordinate of the lower left 
voxel and the voxel size.

How do you set the coordinate for another corner (e.g., upper right) so 
the coordinates
run in the direction I want using the fixed voxel size I have?  Right 
now it seems to just
increment in the x,y,z dimensions by the voxel size and the coordinate 
of the upper right
is not correct (my volume is slightly oblique for lack of a better phrase).