How to use SpatiaLite functions in a Python script?

I'm trying to find the intersection coordinates between a line (knowing its start and end points) and a polygon (SQlite file).

I've managed to make it work in QGIS by creating a shapefile for the line and then using DBmanager and the following SQL statement:

SELECT astext(st_intersection(polygon.geom, line.geom)) as XY

from polygon, line
WHERE st_intersects(polygon.geom, line.geom)

It works just fine but now I'm trying to make it work in a python script with the XY coordinates of the line and the polygon.sqlite file as inputs.

I'm trying to write the code and I've come to this so far:

#!/usr/bin/env python
# -*- coding: UTF-8 -*-

import gdal
import ogr

import sqlite3
import math
import shapefile
import pyspatialite



fichier=open("C:\\MyPath\\polygon.sqlite","r")
connR =sqlite3.connect("C:\\MyPath\\polygon.sqlite")


curR =connR.cursor()

#trying to add a table for the line:

curR.execute("""
               CREATE TABLE my_line(
                   id INTEGER PRIMARY KEY,
                   XMin INTEGER,
                   YMin INTEGER,
                   XMax INTEGER,

                   YMax INTEGER,
                   geom MULTILINESTRING
                )
""")
connR.commit

# user coordinates inputs

XA=input('X A = ');
YA=input('Y A = ');

XB=input('X B = ');
YB=input('Y B = ');

curR.execute("""INSERT INTO route VALUES (?,?,?,?,?,?)""", (1, XA, YA, XB, YB,"MULTILINESTRING"))
connR.commit()

#trying to use SpatiaLite functions:

curR.execute("""
        SELECT astext(st_intersection(polygon.geom, line.geom)) as XY

        from polygon, line
        WHERE st_intersects(polygon.geom, line.geom)
""")
connR.commit()

As you can see, my first problem is that I don't know how to create a "line" object in the table 'my_line'. My second problem is that I don't know how to use the SpatiaLite functions in a python script.