  We have modeled the injection and acceleration of pickup ions at the solar
wind termination shock and investigated the parameters needed to produce the
observed Anomalous Cosmic Ray (ACR) fluxes. A non-linear Monte Carlo technique
was employed which in effect solves the Boltzmann equation and is not
restricted to near isotropic particle distribution functions. This technique
models the injection of thermal and pickup ions, the acceleration of these
ions, and the determination of the shock structure under the influence of the
accelerated ions. The essential effects of injection are treated in a mostly
self-consistent manner, including effects from shock obliquity, cross-field
diffusion, and pitch-angle scattering. Using recent determinations of pickup
ion densities, we are able to match the absolute flux of hydrogen in the ACRs
by assuming that pickup ion scattering mean free paths, at the termination
shock, are much less than an AU and that moderately strong cross-field
diffusion occurs. Simultaneously, we match the flux ratios He$^{+}$/H$^+$ or
O$^{+}$/H$^+$ to within a factor ~ 3. If the conditions of strong scattering
apply, no pre-termination-shock injection phase is required and the injection
and acceleration of pickup ions at the termination shock is totally analogous
to the injection and acceleration of ions at highly oblique interplanetary
shocks recently observed by the Ulysses spacecraft.
