Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See Parameter IDs.
Parameter: TBP_PART_JOINTS
TBP_PART_JOINTSParameter: P
TBP_PART_JOINTS_POSITIONTRANSFERParameter: R
TBP_PART_JOINTS_ROTATIONTRANSFERParameter: S
TBP_PART_JOINTS_SCALETRANSFERParameter: UD
TBP_PART_JOINTS_USERDATATRANSFERParameter: UD Mode
TBP_PART_JOINTS_USERDATATRANSFER_MODEParameter: TBP_PART_CONTROLS
TBP_PART_CONTROLSParameter: TBP_PART_INCLUDESTRING
TBP_PART_INCLUDESTRINGParameter: TBP_PART_EXCLUDESTRING
TBP_PART_EXCLUDESTRINGParameter: TBP_PART_IDENTIFIER
TBP_PART_IDENTIFIER