Take the A26 from Calais to Troyes – A5/A31 then A6 to Dijon – A6 to Lyon – A43/48 to Grenoble – N91 to Briancon. Once in Briancon follow “Toutes Directions” and then Gap/Sisteron. You go round Briancon and then out on the main road heading south on the N94. Approximately 5 kilometres past Briancon and after a main roundabout, at the village of Prelles, take a right-hand turn signposted to Puy St. Vincent (and Les Vigneaux and Vallouise). Follow this minor road for 15 minutes all the way to Les Vigneaux. Drive straight through this little hamlet to the main road to Puy St. Vincent/Vallouise. Turn right at the obvious T-junction signposted Vallouise/Puy-St-Vincent and turn straight away left to Puy St. Vincent. Another 5 minute climb and you'll reach your destination.
Lyon - Chambery - Fréjus Tunnel - Col De Montgenèvre - Briancon - Vallouise: The Frejus Tunnel is about the same time wise as the Col Du Lautaret but a lot more expensive due to the tunnel toll (€40 in 2013). Plus it's a bit like driving through an elongated coffin, and why you’d want to pay for that I don’t know.