If you are driving from Milan to Livigno be careful what route you take. On the maps there are some routes that look like short cuts but the passes are either shut in winter or close at particular times during the day.
The best route from Milan is Milan - Tirano - Bormio - to the Foscango Pass - follow signs to Livigno. You have to give yourself about 5 hours excluding any stops for lunch etc. Here is what is said on one of the tourist information pages:
From Milan, at the exit of the highway, enter the State Route 36 Milan-Lecco-Colico, entirely with two roadways, end continuing with the State Route 38 “dello Stelvio” until Tirano (165 km). From there the road continues to Bormio (207 km) and to Livigno (237 km).