Take to an LBS that has a Phil Wood, Morizumi or Kowa spoke cutting and thread rolling machine. It's best to keep the reduction to 2mm or larger.

Usually trying to do only 1mm reduction and threading is problematic.

Phil can do it - just the end user needs to be certain they thoroughly clean the work recess of the bits before take down, cleaning and reassembly. Else they get mashed between the body parts. They can also jam the flipper.

The Kowa can do it - however the cutter hole gets filled by the 1mm piece left behind requiring a firmer snap of the next spoke in order to cut the next spoke AND clear the old piece. The cycle repeats itself for the next pair of spokes in order. The nice thing though is the Kowa picks up the existing leftover threads extraordinarily well.

Try to see if a 2mm reduction minimum is doable for this job - it'll be easier for the mechanic to handle than a 1mm reduction.

Can't comment on the in's / out's of this in regard to the Morizumi even though it's similar to the Kowa..

=8-)