Backupmenu is what I'm just learning to use... So to make a root-enabled rootfs image, I have to install rootsh first, then back up rootfs using backupmenu, and finally convert the rootfs image to what I can flash with flasher-3.5, is that right?
Also, does this mean I can even pre-install other softwares (e.g. Faster Application Manager) and make a custom rootfs with them included?