If you have Windriver installed (and updated) (either on a different computer, in Parallels or with Bootcamp), there's a zip file with the source at C:\WindRiver\WPILib (or wherever you installed it at). The latest version I could find is dated 2012-02-04.
You can get the same by downloading the
update package and extracting it. I do this with
7-Zip (which has unofficial builds available for Mac OS X), but other compression software may be able to as well.
__________________
FRC 2046, 2007-2008, Student member
FRC 1708, 2009-2012, College mentor; 2013-2014, Mentor
FRC 766, 2015-, Mentor