After reading the tutorial at http://surfer.nmr.mgh.harvard.edu/fswiki/FsTutorial/Talairach, I understand that I should be using 
"tkregister2 --mgz --s SUBJECT --fstal --surf orig" when editing my talairach transform.  I have been somewhat successful at this, but I was wondering if there might be another way to adjust talairach registration, perhaps by specifying anterior/posterior commissure alignment, etc?