From Ben Gurion Airport the best way is a shared taxi (NESHER) which will drop you off right at the door of the apartment. You can find them outside of the main arrival hall, on the right side. A single ride to Jerusalem costs 64 NIS and takes about 30-40 minutes (depending on the traffic). The house is next to the Bike Shop and just before the steps next to number 29 (there are 2 number 27 which might be confusing).