I'm not an airline pilot, however just like Iainhol and I have to do when taxiing a small aircraft into position on the runway, I'm sure the Big guys just simply roll the aircraft forward a few feet along the center line untill she looks straight.
General Aviation pilots use rudder pedals to steer with while taxiing, and airliners use a small "Tiller" wheel (steering wheel) to steer. This tiller wheel is located on the left seat pilot's left side pannel.
Who knows...maybe these small tiller wheels are marked, to indicate to the pilot when the nosewheels are pointed straight. However, that won't nessesarily mean that the aircraft is.