Information on how to get to CERN is given here: http://user.web.cern.ch/User/Institute/Integration/GetToCERN/GetToCERN.html. The IT auditorium is located here: http://building.web.cern.ch/map/building?bno=IT+AUDITORIUM:+31-3-004.
Attendees that need a CERN access card should ask the chairperson. The badge should be got at the Reception (building 33) upon arrival. For whose who need to book a room, there is some information on that page: http://housing-service.web.cern.ch/housing-service/index.html. No reservation or pre-booking has been made.