0. Install the correct drivers (ADB, MiFlash/MiPcSuite, Qualcomm,..)
1. Request unlock permissions
2. Flash china dev
3. Unlock with MiUnlock Tool
4. Flash TWRP with fastboot and ADB
5. Put the rom in to the phone and from TWRP flash it
6. Start the phone and enjoy the MIUI by Xiaomi.eu
But...