To counter the yawing from the engine failure, boot in opposite rudder to keep the arrest yawing and restore original heading; if the engine fails right at rotate, you might want to either keep the nose on the runway until you reach V2 (you said it was just before the main wheels lifted off, just lower the nose a touch) or if you already are in the air, flatten out the climb a little bit to help you accelerate better until you reach V2 then proceed from there. There should be enough power on the opposite engine to maintain a sufficient rate of climb, I suppose you can run the opposite engine up to 100% N1 to help things out a little though.