Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See Parameter IDs.
Parameter: Count
MG_LINEAR_COUNT
Parameter: Offset
MG_LINEAR_OFFSET
Parameter: Mode
MG_LINEAR_MODE
Parameter: Amount
MG_LINEAR_OBJECT_AMOUNT
Parameter: P
MG_LINEAR_OBJECT_POSITION
Parameter: R
MG_LINEAR_OBJECT_ROTATION
Parameter: S
MG_LINEAR_OBJECT_SCALE
Parameter: Step Mode
MG_LINEAR_JOINT_MODE
Parameter: Step Size
MG_LINEAR_JOINT_SCALE
Parameter: Step Rotation
MG_LINEAR_JOINT_ROTATION