Root IS required !!
This mod will add init.d support to any rom even stock roms without editing the ramdisk. Instead it uses the post_boot.sh file that is in most if not all roms. It should work on most devices, if it does not work on yours please look in /system/etc and post the name of the file that contains "post_boot.sh".
This mod has been tested on the OneX and OneS.
To use just flash in recovery and add your favorite scripts to init.d.
For devs:
To add this method to your rom simply edit the post_boot.sh file and add this line at the bottom:
Easy right ? Suprised it hasn't been done before, well at least that i know of.
All files in init.d will be executed at boot just like regular init.d. You can also manually add the line and make it whatever directory you want.
I have attached a test file to flash to see if init.d is working.
Flash Init_D_Test.zip in recovery
Reboot and navigate to /data and look for a file called Test.log if it's there Congats init.d works.
Download:
http://goo.im/devs/smokin1337/Mods/Easy_InitD_1.1.zip