Scripts ->
https://github.com/ReaTeam/ReaScripts
JSFX ->
https://github.com/ReaTeam/JSFX
Follow the 4 steps explained in the README file ("Contributing"). I just finished updating the
packaging docs for the new features of v1.1.
If you have questions, just ask on the development thread:
http://forum.cockos.com/showthread.php?t=169127.