  We describe the implementation of supersymmetric processes in the HERWIG
Monte Carlo event generator. We define relevant parameter and mixing
conventions and list the hard scattering matrix elements. Our implementation is
based on the Minimum Supersymmetric Standard Model, with the option of R-parity
violation. The sparticle spectrum is completely general. Both hadron-hadron and
lepton-lepton collisions are covered. This article supplements a separate
publication in which the general features of HERWIG 6.2 are described, and
updates the treatment of supersymmetry to version 6.4.
