I have only a printout, but the calculation of the specular illuination is the following:

point Nf = normalize(faceforward(N,I);
point delta = normalize(dPdu);
color spec = specular(Nf-delta,I,roughness);
ci = Cs*(Ka*ambient() + Kd *diffuse(Nf)) + Ks specularcolor spec;

I dont have seen a render with this shader, so I dont know if it is any good, but it gave me the idee to explore the anisotropic node a bit more. I try to use the available wealth of information about renderman shader as inspiration for poser shaders, but I was not really successful in translating anything nontrivial.
Maybe I should try to actually program some renderman shaders first, just to get a better feeling for them.