Hi. You need to root the S4 Mini and then you will need to load the CWM custom recovery automatically using an app called ROM Manager or manually by downloading and flashing the recovery.img using an app call Flashify. Then see the video here:
https://www.youtube.com/watch?v=80oqp1Xh59E
https://www.youtube.com/watch?v=80oqp1Xh59E