I personally believe that if you take the time to decide in your own mind the person you would like to be with, with as much detail as you can put into the image you create, then the non-negotiables will take care of themselves.
Also once you get to know someone pretty well it is easy to ask how they feel about most any subject. As long as you are asking I believe you will get the answers. I don't think saying "this is the points I will not negotiate on" will make you anything but adversarial.
It's my opinion that people enjoy talking about themselves. If you just ask and listen you will shortly know their non-negotiables
