Almost any lathe with change gears can be set up to cut very long threads. In your case it would be a matter of playing with the gears until you get close to what you want.
You could use just a normal pointed cutting tool to give you the groove, it is only for oil transfer, and I don't think it would complain about the shape of the groove.
Your main problem will be when you turn your machine on to do the cutting and then press down on the half nut lever, if it gets that far, your change gears will most probably disintegrate before your very eyes, or some other very nasty and expensive noises and breakages.
With these very long pitch threads, you turn the power off to the machine, and do it all by hand by turning the leadscrew. Some lathes actually have a handle on the tailstock end of the leadscrew, mainly for manually feeding the saddle, but in this case, it would be perfect for the job. You might even get away with turning the lock nuts on the leadscrew end with a ratchet spanner or some such thing.
By doing it that way takes all the pressure off the gear train and you will find it will cut very nicely indeed.
Bogs
