The venue is in the city centre and is a short walk from the Duomo (metro lines M1 and M3) and the Metro station Missori (line M3).
Some useful links:
From Linate Airport (LIN): Bus to Piazza San Babila (digit 73 to search the route).
From Bergamo Orio Al Serio Airport (BGY): Bus to Milano Centrale and then M3 to Duomo.
See the maps below for details. Milan local transport is also well documented on Google Maps (including timetables).
Map of conference site and directions for the venue (click on the image to enlarge):
Map of the conference site and some hotels