The most convenient option for participants will be to fly into Montreal International Airport (YUL). The airport is approximately 45 minutes by car/bus from the conference center and hotel.
For the adventurous, another possibly cheaper option is to fly into Burlington Airport in Vermont and make the 1.5 hour drive (across the border) to Montreal. While less convenient, it is not uncommon for the Burlington flight + rental car to be substantially cheaper than flying into Montreal.
Taxi. From the Montreal airport, taxis are readily available. A one-way ride to downtown will cost approximately $40 CAD.
Bus. Regular bus transport (approx $7 CAD per ticket) is also available by bus #747 which drives directly downtown.
Rental car. The usual choice of major rental car companies are available at the Montreal airport as well. It is worth noting, though, that Montreal is an exceptionally easy city to traverse by public transit, foot, and rental bike (which are available everywhere).