Draw Plane with Plane Equation

I have a plane equation in the form of Ax + By + Cz + D. I’d like to use this to draw a really big quad, essentially an infinite plane, to use with a stencil trick - http://www.opengl.org/resources/tutorials/sig99/advanced99/notes/node21.html

What’s the best way to draw such a plane? For some reason I can’t think of the best way to generate the 4 vertices.

you can find out where the four rays from the camera viewpoint to the screencorners intersect the plane. these will give you 4 points to use as a quad.

stencil trick?
hmm in that case i think the best way is to just change the projection method into a 2d orthogonal one and just draw a plain quad over the whole screen, much simpler

glBegin( GL_QUADS );
glVertex2f(1,0); etc