The prerequisites for steering is that the nose wheel is physically within a few degrees of being straight, and nose wheel steering has been armed (with hydraulics available, etc.), i.e., following the checklists will get you there.
As far as sim controls is concerned, an axis bound to nose wheel steering is supported and will be automatically detected and engaged upon first use in each flight. However, if a dedicated axis is not available, then the full steering will be available from a yaw axis control (not realistic but an accommodation for limited sim hardware users).