Well you know the lock nut distance will be 135mm (I guess, might be 130 or 126 if it's real old), so just measure the length of the axle, take 135 from it, half the result and that's how much axle there will be at each end. Start with one of the lock nuts, add any spacers, fit the cone, then the hub, then the other cone, more spacers and the other lock nut, easy.