Dirk,
This is obviously not a standard 60 degree "V" thread, so even if the diameter and pitch are standard your chances of finding a threading die are essentially nil I believe. If you have a thread gauge (you may need both imperial and metric) you can probably determine the thread pitch accurately enough to single point the thread you need on a metal lathe by making a custom square ended tool. Keystock is cheap and would work well. This assumes that you can configure the proper gearing on the lathe.
Another possibility is to cannibalize the barrel thread component from a standard Tycoon. Threads may or may not be the same.
Finally, you could try to convince your client that he doesn't need the threads. Pelikan doesn't use them.
Happy days,
Bill