To generate a line without the use of CAD data:
Select the desired point in the list in the BASICSCAN dialog box (Insert | Scan | Axis).
Take a hit on the part. This completes the values for that point.
The CutVec is the normal vector of the plane in which the straight line lies.
For more information about the BASICSCAN dialog box and the axis basic scan, see "Performing an Axis Basic Scan".