  A recently introduced percolative theory of unipolar organic
magnetoresistance is generalized by treating the hyperfine interaction
semiclassically for an arbitrary hopping rate. Compact analytic results for the
magnetoresistance are achievable when carrier hopping occurs much more
frequently than the hyperfine field precession period. In other regimes, the
magnetoresistance can be straightforwardly evaluated numerically. Slow and fast
hopping magnetoresistance are found to be uniquely characterized by their
lineshapes. We find that the threshold hopping distance is analogous a
phenomenological two-site model's branching parameter, and that the distinction
between slow and fast hopping is contingent on the threshold hopping distance.
