Add 9/16" to X. Record this measurement.
Cut the threaded end of the spout so that it extends 9/16" + X from the rear of the flange.
Remove the aerator (1).
Wrap the threads on the spout with Teflon tape.
Install the sealing ring and spout. Use a rod or dowel inserted into the end of the spout to assist in tightening it (2).
Do not overtighten the spout, or damage may result.
Tighten the spout flange against the wall (1). Install the aerator (2).
Push the sealing ring and handle over the rough.
Rotate the handle flange clockwise, so that it threads down over the extension spindle (3).