Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See Parameter IDs.
Parameter: Set Reference Pose
CD_SETREFERENCEPOSEParameter: Go to Reference Pose
CD_GOTOREFERENCEPOSEParameter: Open Manager
CD_OPENMANAGERParameter: Create Solver
CD_CREATESOLVER