You can make the same
Push = Bolean Difference function
Pull = Extrude function
Add = Bolean Addition function

I will make you a little video ;) unzip and launch the HTML file
the "Push function" 2 méthods
http://www.mediafire.com/download.php?qyjzynowzzf : intersection with a volume
http://www.mediafire.com/download.php?m32fiz3ehwn : extude line = volume