Is this even possible? Does anyone know how to do it? I haven't figured out how yet.

/navroute add "Ukari A-10" still works, thankfully.

I don't think it's possible currently. I'm not very familiar with how the iup.navmap control works, though. I think what would be ideal is if long-pressing a sector added an intermediate jump point.

Tried it before and it didn't work.