by tram : 13 or 15 stop Butini and from there it's a five minute walk straight to the compound.
by bus: line 1 stop Secheron , this will take you directly to the entrance of the Institute
We will shortly put up a map on which we will have indicated both places
Here is a link to the site of the TPG "Transport Public Genevois" (Geneva Public Transportation. Unfortunetly it's in French, but it will show you the itineries of both tram lines as well as the buses. It also has information as to tickets and prices. A normal ticket will cost you 3 CHF