OK, if you are sitting in the pilots' seat and look off to the right, that would be the direction to cock the engine for right thrust. If you look down at your feet, that would also be the direction to point the engine for down thrust. The tricky part is to grind both angles into your engine mount or to position the firewall with both angles included. I would favor having the firewall set at zero-zero and work over a $4 engine mount to get the desired angles.