To port my keyboard layout [0] to OSX, I used ‘osxkb’ [1], which outputs an OSX keyboard layout bundle given a simple textual specification file. It was originally created specifically to port Conkey to OSX, but should be entirely usable for other purposes as well.

[0] https://github.com/bradrn/Conkey

[1] https://github.com/akamchinjir/osxkb