I have seen a couple of people asking why they can't do wireframe renders in XSI. Well you can, there is a little camera icon at the top of the camera viewport. Clicking on this will give you a menu with an option to start capture. This will bring up a dialog box that will allow you to render out wireframe, shading, textured, constant, whatever you have the viewport set to.
it gives you the option to antialias it though and you can still composite it onto something or worse case key out the backgroud to get an alpha channel
In the rendertree, double-click the Toon_Wire shader to open up its property page. Click on the "Toon_Wire" tab, under Facet is a box labeled "Ink Lines."
thanks! i searched at a total different place. btw it changes quadrangles into triangles and automatically removes hidden lines without any option to change it.