1. Make sure you have Jellybean Installed on the device. If not then install the JB on the device.
2. If you have installed JB just now then start the device and go through the setup.
3. Make sure you have CWM based recovery. If you do then go to the CWM recovery and
i. Wipe Cache
ii. Wipe Dalvik Cache
iii. Wipe DATA/Factory Reset4. Flash the MIUI rom and then restart the phone.
If you have Any problems then please reply here on the thread. I am using the MIUI for a long time on Knight and I am very happy from the results. I will be more then happy to help you if you find any problems.
Hit Thanks if you find this helpful.