From PCOM:

Take City Ave. North to Lincoln Drive.; Take Lincoln Drive to first light, and turn Right onto Rittenhouse Ave.; Take Rittenhouse to the second light, turn Left onto Wayne Ave.; Take Wayne Ave. to the second light, turn Right onto W. Walnut Lane.; Phi Sig is the second house on the right. 270 W. Walnut Lane.

From Main Street Manayunk:

Take Shurs Lane (at intersection in front of Chemistry).  Schrs Lane turns into Walnut Lane.  Follow to Wayne Ave.  After light, pull into first driveway on right. 270 W. Walnut Lane.