From Boston's Logan Airport take the Sumner Tunnel to Storrow Drive. Take Storrow Drive to Kenmore Square, where you get onto Beacon Street and proceed through Brookline.
From the airport follow the signs for the Sumner Tunnel (called Callahan Tunnel in the other direction). Do not take the Ted Williams Tunnel, which takes a different route. While in the Sumner Tunnel you will see signs for Storrow Drive. Exit from the tunnel in the Storrow Drive lane and keep to the right as the underground ramp feeds you onto Storrow Drive without even getting into the parallel traffic stream for I-93 North.
Stay on Storrow Drive until the Kenmore Square exit (Kenmore is the 4th left exit on Storrow Drive). Immediately after exiting, stay to the right at the fork. At the first light turn right onto Beacon Street. At the second light on Beacon Street, choose the middle of the three options (12 o'clock) to continue on Beacon Street (not 10 o'clock leading to Brookline Avenue or 2 o'clock leading to Commonwealth Avenue).
Continue along Beacon Street for 2.7 miles from Kenmore Square, following the instructions on the driving directions from Beacon Street page.