  We present a systematic comparison of doubly charged Higgs boson production
mechanisms at hadron colliders in the context of the Type II Seesaw model,
emphasizing the importance of higher-order corrections and subdominant
channels. We consider the Drell-Yan channel at next-to-leading order in QCD,
photon fusion at leading order, gluon fusion with resummation of threshold
logarithms up to next-to-next-to-next-to-leading logarithmic accuracy, and
same-sign weak boson fusion at next-to-leading order in QCD. For Drell-Yan
processes, we study the impact of a static jet veto at next-to-leading order
matched to the resummation of jet veto scale logarithms at
next-to-next-to-leading logarithmic accuracy. For the photon fusion channel,
the dependence on modeling photon parton distribution functions is definitively
assessed. To model vector boson fusion at next-to-leading order, we include all
interfering topologies at $\mathcal{O}(\alpha^4)$ and propose a method for
introducing generator-level cuts within the MC@NLO formalism. Our results are
obtained using a Monte Carlo tool chain linking the \textsc{FeynRules},
\textsc{NloCT} and \textsc{MadGraph5\_aMC@NLO} programs and have necessitated
the development of new, publicly available, Universal FeynRules Output
libraries that encode the interactions between the Type II Seesaw scalars and
Standard Model particles. Libraries are compatible with both the normal and
inverted ordering of Majorana neutrino masses.
