My FSX was set up with a "power hanger" style widget when I ran canti's on it, and the setup worked well once you got things sorted out. when V-brakes came out, however, I was more than happy to remove and forget about the vile thing.
Making a repro of the original Judy style hanger as shown in posts above should be easy for anyone with a tap and die set and a drill press, a hacksaw and a file. I'd think an enterprising individual could knock one out in about an hour, starting with some 3/8" or so alu bar stock.
Chuck stock in drill press, use file to size the end that must seat in the fork brace. Bore that end and thread the hole. Bore the cableway, then bore the stop. Cut the cable slot with hacksaw, find a suitable bolt and Bob's yer uncle.
J