  Models of relativistic heavy ion collisions typically involve both a
hydrodynamic module to describe the high density liquid-like phase and a
Boltzmann module to simulate the low density break-up phase which is gas-like.
Coupling the prescriptions is more complicated for viscous prescriptions if one
wants to maintain continuity of the entire stress-energy tensor and currents.
Derivations for the viscosity for a gas are reviewed, which then lead to
expressions for changes in the phase space occupation based on simple
relaxation-time pictures of viscosity. These expressions are shown to
consistently reproduce the non-equilibrium components of the stress-energy
tensor. An algorithm for generating a Monte Carlo sampling of particles with
which to initiate the Boltzmann calculations is also presented.
