Originally Posted by eclyptos
This part is not clear to me. If I installing the Recovery on non rooted device, how the recovery will root it at the same time? I will still have recovery without root.
Option 3 > installation on unrooted ROM.
Because the installation script can gain a temporary root shell
It uses that to install the dual recovery
then its as simple as flashing SuperSU.zip or a pre rooted rom to gain "Full" root.