Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See Parameter IDs.
Parameter: Visible Only
MDATA_KNIFELINE_VISIBLE_ONLYParameter: Slice Mode
MDATA_KNIFELINE_SPLIT_MODEParameter: Single Line
MDATA_KNIFELINE_SINGLEParameter: Infinite Cut
MDATA_KNIFELINE_INFINITEParameter: Restrict to Selection
MDATA_KNIFELINE_SELECTEDParameter: Select Cuts
MDATA_KNIFELINE_SELECT_CUTParameter: Connect Cut Edges
MDATA_KNIFELINE_CUTPOLYSParameter: Preserve N-gon Curvature
MDATA_KNIFELINE_NGON_CURVATUREParameter: Auto Snap
MDATA_KNIFELINE_AUTOSNAPParameter: Angle Constrain
MDATA_KNIFELINE_ANGLE_CONSTRAINTParameter: Angle
MDATA_KNIFELINE_ANGLE_CONSTRAINT_VALUEParameter: Realtime Cut
MDATA_KNIFELINE_REALTIME