The original HW has been supported in the uTasker project - http://www.utasker.com/kinetis/TEENSY_3.1.html
and support for the new HW has been prepared (including KBOOT support) - http://www.utasker.com/kinetis/TEENSY_LC.html
The Teensy HW has proven to be surprisingly popular for development work so it will be interesting to see how the new KL26 based version fares...
Kinetis: µTasker Kinetis support
For the complete "out-of-the-box" Kinetis experience and faster time to market