[Freesurfer] manual parcellation of labels

Hi,

I want to divide my cingulate labels into anterior and posterior cingulate labels. This divison is based on a line perpendicular to the AC-PC axis, and through the AC.

Currently, I am trying to do this by using csurf and clicking and saving points along the Tal = 0 coordinate within the midsagittal plane of the tkmedit view. I then go to the points in the tksurfer view and then draw a line here to create a new label. It seems that there must be an easier way of doing this using the code that csurf employs to link the volume and surface coordinates.

If you could suggest a method for automating this, I would greatly appreciate it.

Thanks, Avinas