When you buy the small round packs of the braided stainless leader at Bass Pro the packs have about 10 of the correct size ferules for the wire. I also keep sticks of aluminum tube in my shop and cut about an 1/8 or 3/16 piece of that to use. When a friend closed his hobby shop I got the display with all the tubing and there isn't a lot of call for it.
Ackerman: the best description of how to set up a pull/pull system with Ackerman I have ever see was in a modeling magazine a couple years back. All the math detail was removed from the article and it was more of a how to do article with a couple photos. I [think} it was model airplane news? Could have been RC Report though? I have friends that save me there old magazines and I get almost all of them at some point, usually all at one time so I can't keep up with where I see things. Last magazine I subscribed to was RC Report.