arcpy.CheckOutExtension("LocationReferencing")
inputEventFC = r"c:\EnableReferent\Py\EnableReferent.gdb\LRS"
fromReferentMethodField = 'FromRefMethod'
fromReferentLocationField = 'FromRefLocation'
fromReferentOffsetField = 'FromRefOffset'
toReferentMethodField = 'ToRefMethod'
toReferentLocationField = 'ToRefLocation'
toReferentOffsetField = 'ToRefOffset'
offsetUnit = 'FEET'
arcpy.locref.EnableReferentFields(inputEventFC, fromReferentMethodField, fromReferentLocationField,
fromReferentOffsetField, toReferentMethodField, toReferentLocationField,
toReferentOffsetField, offsetUnit)
arcpy.CheckInExtension('LocationReferencing')