Worm Gear Cutting

I have a fairly straightforward question about a worm gear segment. But as of yet, I haven’t gotten a straight answer from any of the gear job shops I’ve approached about this job. Is there a "traditional" gear cutting method that can produce a ~180 degree enveloping worm gear segment when a feature on the back of the part will interfere with a complete rotation of the part? Or am I left with only the option of 4- or 5-axis surfacing with a CNC mill? I have presented this part to several well-known gear shops in the U.S. without a straight answer on how the part can be made. Any help you could offer would be appreciated.