Hi Charles,
Not sure if this is useful to you. I had created the following symbol and footprint when I designed a custom cape in kicad in 2012. It's just the 23x2 pin array with the right diameter and spacing. I would add two of these on the schematic, one for P8 and one P9, and label the pins I actually use. In PCBnew, place them so that their center is 1.9 inch apart. My P8 is centered at (2.2", 4.9") and P9 is centered at (2.2", 3.0").
For the design I had done, the "cape" was much larger than BB. So BB mounts on the cape from above, facing downward. You should flip the footprint if your situation is the opposite.
If you like, I could label the pins and make separate library parts for P8 and P9, or merge both P8 and P9 into a single library part.
George
p.s. I had to rename boneHeader.lib to boneHeaderlib.txt to get through gmail.