  We perform for the Large Hadron Collider (LHC) a detailed study of charged
Higgs boson production via the top-bottom quark associated mode followed by
decays into a chargino and a neutralino, with masses and couplings as given by
the general Minimal Supersymmetric Standard Model (MSSM). We focus our
attention on the region of parameter space where the charged Higgs is heavier
than the top quark, with intermediate values of tan beta. In this region, the
identification of charged Higgs bosons via decays into Standard Model (SM)
particles has proven to be ineffective. Modelling the CMS detector, we find
that a signature consisting of three hard leptons accompanied by a hadronically
reconstructed top quark plus substantial missing transverse energy, which may
result from charged Higgs decays into neutralinos and charginos, can be made
viable over a large variety of initially overwhelming SM and MSSM backgrounds,
provided MSSM input parameters are favourable: notably, a small mu parameter
and light sleptons are important prerequisites. We quantify these statements by
performing a fairly extensive scan of the parameter space, including realistic
hadron-level simulations, and delineate some potential discovery regions.
