do a nandroid backup (CWM backup), then download this zip:
http://db.tt/Zt09T1HB
to create a flashable zip, pull the boot.img and system.ext4 files from the nandroid backup.
Unzip the system.ext file (you will get a system folder full of files)
copy the system folder and boot.img to the zip and rename the zip to whatever you want.
You can get fancy and update the ui print dialogs in the updater-binary script and rom name in the build.prop but you don't need to as these are purely cosmetic and only appear during the cwm install and in the system menu.