Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See Parameter IDs.
Parameter: Count
MG_LINEAR_COUNTParameter: Offset
MG_LINEAR_OFFSETParameter: Mode
MG_LINEAR_MODEParameter: Amount
MG_LINEAR_OBJECT_AMOUNTParameter: P
MG_LINEAR_OBJECT_POSITIONParameter: R
MG_LINEAR_OBJECT_ROTATIONParameter: S
MG_LINEAR_OBJECT_SCALEParameter: Step Mode
MG_LINEAR_JOINT_MODEParameter: Step Size
MG_LINEAR_JOINT_SCALEParameter: Step Rotation
MG_LINEAR_JOINT_ROTATION