How to use nipype freesurfer interface Smooth in openfmri?

This preproc script

uses nipype’s create_featreg_preproc

which in turn calls Susan smoothing.

I’d like to remove Susan smoothing and instead use the Smooth node from here:

but the smooth node requires a register.dat. As I understand it, register.dat is created by but not until after preprocessing has occured. Do I need to run the script twice in order to get that reg.dat or am I missing something?