[firedrake] Interfacing directly with PETSc

hi, i am wondering if the method to interace PETSc ( http://www.firedrakeproject.org/petsc-interface.html) would also work in parallel? i tried a slightly modified code (since i am using dolfin at the moment), which works on one processor but fails in parallel. Is there an easy way to pack a sequence of dolfin / firedrake operators into one parallel petsc opterator (matshell) thanks a lot best wishes Florian Bruckner