afni.nimh.nih.gov

I was wondering whether someone has done the following:
1. Mask a certain area in the brain using the drawing routines.
2. Obtain the overall volume of the area drawn.
3. Align the images in AC/PC space
4. Get a fractional volume from anterior to posterior

If anyone has any suggestion how to implement this with a combination
of 3dcalc, 3dmerge or 3dROIStat routines that would be great.