Just tried and I got a temp root with Weaksauce from the M8 forums, which allowed me to run firewater for S-Off on the 4.4.2 ota.
1.) Install the necessary drivers
2.) Install and gain temp root with weaksauce, from this thread: http://forum.xda-developers.com/showthread.php?t=2699089
3.) After obtaining Temp root (TuneInRadio will appear in your notification bar if its running) Run Firewater (normal, rooted device method) and your golden: http://firewater-soff.com/instructions/
Make sure to follow all the instructions for Weaksauce and Firewater.
1.) Install the necessary drivers
2.) Install and gain temp root with weaksauce, from this thread: http://forum.xda-developers.com/showthread.php?t=2699089
3.) After obtaining Temp root (TuneInRadio will appear in your notification bar if its running) Run Firewater (normal, rooted device method) and your golden: http://firewater-soff.com/instructions/
Make sure to follow all the instructions for Weaksauce and Firewater.