Driving around the north-eastern edge of Paris might be an absolute nightmare, but it would depend upon the time of day. Follow the links from this page for reports of varying experiences on the route:
http://www.beauvais-airport.com/Disneyland-Par is/Driving-Beauvais-Airport-Disneyland-Paris.p hp
(On the first link, you need the post from Anne Simpson).
Links to various shuttle companies can be found here:
http://www.beauvais-airport.com/Disneyland-Par is/
However, looking at the prices mentioned on that page (and assuming that you're the same questioner who recently mentioned a family of 4 making this trip), it looks as if you might find it would cost about the same (or possibly less) to take a taxi. It still won't be cheap, at around �170 (�120) each way during the day, or �230 (�160) at night:
http://www.aeroportbeauvais.com/taxi.php?lang= eng
Chris