So, I have tested this myself.
Download a developer ROM from en.miui.com : http://obigota.d.miui.com/5.10.16/miui_MI4c_5.10.16_3be1109680_5.1.zip
Flash the Dev ROM from the updater app. You should have root access after installing the Dev ROM.
Install Flashify from Playstore then provide root...