No, more like:
(Where FFrustumPlane is the corner points that needs to be calculated first)
[pascal]
var
I: Integer;
begin
glBegin(GL_QUADS);
for I := 0 to 5 do begin
// Quad consists of 4 points
glVertex3fv(@FFrustumPlane[I].p1);
glVertex3fv(@FFrustumPlane[I].p2);
glVertex3fv(@FFrustumPlane[I].p3);
glVertex3fv(@FFrustumPlane[I].p4);
end;
glEnd();

{
glVertex3fv(@FFrustumPlane[I].p1);
means the same as
glVertex3f(FFrustumPlane[I].p1.x, FFrustumPlane[I].p1.y, FFrustumPlane[I].p1.z);
}[/pascal]

If you would only use mathematical plane (like your frustum plane currently is, by 4 values defining the entire plane) formula to define the quads, you would need to calculate 4 plane intersection lines. And then intersect those with the remaining 2 planes to get the corner points... which is all complicated and i wouldn't even try that way :lol:

Search out definitions for modelview and projection matrix and see if there's perhaps something that you could use to directly calculate corners. And actually this way doesn't seem to be simple either