Cut the cue in half
Put the butt half in your lathe, face the joint, then bore and tap a hole for the joint pin.
Install the pin.
face off the shaft, bore and cut threads or put in an insert.
The holes and threads have to be dead nuts, and you have to face the ends with the cue turning perfectly, or it will be crooked and noticably off-center.
If you find some used equipment and tooling you could probably make some nice sneaky petes from old house cues for about 5 grand.