  We set up the Kosower, Maybee, O'Connell formalism for generic spin following
a previous field theory construction and use it to extract a next-to-leading
order eikonal formula for the linear-in-spin momentum impulse, $\Delta
p^{\mu}$, and spin kick, $\Delta S^{\mu \nu}$. We explicitly test the formalism
for the case of electrodynamics and find agreement with previous QFT and
worldline results. This includes the case where multiple spins propagate with
allowed spin transitions, or equivalently where no spin supplementary condition
is imposed on the worldline equations of motion.
