We study the pair-production of charginos in the CP-violating Minimal Supersymmetric Standard Model at center-of-mass energies around the heavy neutral Higgs boson resonances. If these resonances are nearly degenerate, as it can happen in the Higgs decoupling limit, radiatively induced scalarpseudoscalar transitions can be strongly enhanced. The resulting mixing in the Higgs sector leads to large CP-violating effects, and a change of their mass spectrum. For longitudinally polarized muon beams, we analyze CP asymmetries which are sensitive to the interference of the two heavy neutral Higgs bosons. We present a detailed numerical analysis of the cross sections, chargino branching ratios, and the CP observables. We obtain sizable CP asymmetries, which would be accessible in future measurements at a muon collider. Especially for intermediate values of the parameter tan β, where the largest branching ratios of Higgs bosons into charginos are expected, this process allows to analyze the Higgs sector properties and its interaction to supersymmetric fermions. *