From San Francisco Airport:

Take the 101 Freeway - South (towards San Jose)
Merge on US-101 SOUTH
Take the CA-92/FASHION ISLAND BLVD exit towards HAYWARD
Take the HESPERIAN BLVD exit towards SAN LORENZO
Turn Right on HESPERIAN BLVD
Continue on UNION CITY BLVD
Make a U-Turn on UNION CITY BLVD

From San Jose Airport:

Start going towards the AIRPORT EXIT on AIRPORT PKY
Continue on E BROKAW RD
Turn Right to take the I-880 NORTH ramp towards OAKLAND
Merge on I-880 NORTH
Take the INDUSTRIAL PKWY/WHIPPLE ROAD exit
Turn Left on WHIPPLE RD
Turn Right on UNION CITY BLVD