there should be an extrude modifier available for poly editing. just grab a face and pull it out.
refining by boolean means taking 2 objects and 'bool-ing' them.
you can volume merge, add, subtract, exclude, etc.
you can also ignore volumes and just use 'refine'. this basically means take object A, and object B, and everywhere object B intersects object A, cut it there (i.e. split the faces with a new line). afterwards you can then select the faces you wish (like the newly refined-in faces on object A... which would be inside the area once occupied by object B) and extrude them.
-scheherazade