To get to campus from the railway station (or from downtown), take the tramway. Tram tickets must be bought before you board ; vending machines at all tram stops accept coins, and bank cards compatible with the French chip system.
Take tram line 1 in the direction "Mosson", and get off at the stop "Université des Sciences et des Lettres". A 5-minute walk north towards a roundabout with a distinctive red modern art sculpture gets you to the main entrance to campus. The meeting and registration will take place in building 13 Salle Grande Ourse.
(for more info click the campus map here http://indico.in2p3.fr/event/14481/picture/4.pdf))