Floating around the XDA forum is a Kitkat rom / guide. I was able to get the phone up and running but kept getting the error "no sim" or something like that. After I installed the modem from this post it worked fine.
directions and downloads for update sgh-t399 to kitkat
http://forum.xda-developers.com/android/development/rom-lightwave-v1-t2825253/post56059019#post56059019
zip for modem
http://forum.xda-developers.com/android/help/qa-lightwave-v3-t2904537/page3
in short, follow all the steps at the first url - then before rebooting install the zip from inside twrp (etc).
