Open the map compiler and click on the button for advanced options (">>>"), there you'll see a slider "Tesselate flat".
IMO you should not use vertex lighting, though, but use simple point light shaders (without any normalmapping and the like). Then you don't need tesselation anyway.
EDIT: Because vertex lighting always looks bad, no matter how fine your tesselation is, and it's basically only a relict from old A5/ A6 times.
Last edited by Superku; 12/08/11 20:53.