, thanks for your bootloader mod om CML4. Just flashed it with CWM, steps as follows:
1) my Mega had already PhilZ-touch-CWM installed, thus booting into recovery, wipe data+cache+dalvik and install "i9205_kernel_cml4" (mod by shazzl) on SD thru CWM;
2) without leaving CWM install then "UPDATE-SuperSU-v1.80" on SD;
3) reboot via CWM and finish things (wifi, Google a/c, etc) from the Setup pages, go to Apps Drawer select SuperSU then a message pops out asking for knox invalidation, Confirm;
4) do a reboot, update SuperSU to the latest v1.91, install busybox, root explorer, titanium backup, greenify, lucky patcher, etc - all works fine.
NOTE: 2 Red lines show up at top of the Samsung start up screen on every boot, together with a line saying like Warranty: kernel. Also at Settings/About device, SE for Android status goes to Permissive -which is good!!!
I know the knox warranty counter is "010" meaning warranty void but may be some genius devs can work around later, lol. Thanks shazzl again.