twist tie wire and wrapped it around the hanger wire, maybe tin solder it, then cut it off at an angle close to the other wire
Soldering.....whew, man I hope you have plenty of time and a lot of patience because if you need a lot of BW as you stated you're going to be soldering from now until about Xmas

Seriously, take a close look at the build-A-Rama barbed wire, as Aferg said, what they basically have done is to put a small kink in the wire about every 1/8th of an inch or so, and this replicates the "barb" reasonably well. If you have the time to spend soldering each little barb in place, then by all means go for it, but if you are gonna try and "roll your own" so to speak, you may want to try just putting kinks in the wire and see how it looks, just a suggestion, and I'd be interested to see your finished product. Good luck.

Gen. George S. Patton Jr., 28th Regimental Colonel, 3rd Armored Cavalry Regiment, U.S. Army, "Blood and Steel"