How can I get the the position of a tkr voxel in terms of the native voxel space?

My guess was:

pos = Torig*[C R S ones(size(S))]';% orig CRS to tkrRAS
pos = P*pos;% tkrRAS to native RAS
pos = W*bmsk;% native RAS to native CRS

Where,
Torig is given by mri_info --vox2ras-tkr orig.mgz

P is qiven by mri_info --tkr2scanner orig.mgz

W is given by mri_info --ras2vox orig/001.mgz

But that is not returning expected values.

Thank you,

-Burke Rosen