Thanks for all of your very useful help! I think I got everything working OK, but the library files are probably very messy. 
I ended up copying a 24 pin (0.6") DIP socket and using the spacing as a reference but changing the pin names. I then added some more pins on the end for the FTDI and extended the "boundary" (for lack of a better word) to reflect the extra pins.
If you are interested in seeing the finished library, it is here. (https://drive.google.com/file/d/0BwqZI88ckbEYcU5oZG5PRWVwRVE/edit?usp=sharing)
I am planning on making an instructable so I will share it probably in a few weeks when it is finished.