What did l learn from other post and I did is you have to put/replaced customized update.sh on the script folder.And put su file in the file android_fs.tar.systembin and Superuser.apk on the to made it pre-installed. Others eitheryou put ConnectBot or BetterTerminal. But for me I preferto install BetterTerminal after the flashing.Which I think the easiest way to get the file by copy fromother customize rom. Just get their update.sh and su file thenflash your device. Or you can search this bundle package whichI found on another forum.After that flash your customized rom,enable "debug mode" on the application setting,Install BetterTerminal or ConnectBot if you not done that.Then open the terminal application and type su. If it donewell Superuser app will prompt and you allow it. Another waywithout install the terminal app just use adb shell and doingsu with it.