There's a whole procedure laid down how turns should be done. All kinds of visual clues can be used to determine wing tip clearance, distance from main gear to the edge of a surface etc. It requires quite some concentration, and to be honest; cameras would be easier! I need to add as well that minimum turning radius in a 744 is 46.6 meters, so in for places with a runway width of less than that turning pads or intersections with taxiways will need to be used.