Download and Install MIUI 4 Custom ICS ROM for Samsung Galaxy S3

• First of all, download the MIUI 4 custom ICS firmware package for your Galaxy S3 from here – Download Link.
• Turn on USB debugging your Galaxy S III from here – Settings > Applications > Development > USB Debugging.
• Now connect your phone with the computer using a data cable.
• Transfer the .zip file of the MIUI 4 ROM which you have just downloaded, onto your device’s SD card.
• Disconnect your phone from the computer once you have transferred the firmware package onto your phone’s external memory card.
• Turn off your Galaxy S3 and then enter into recovery mode by pressing and holding these buttons for a while – Volume Down + Home + Power.
• Select – Wipe Data/Factory Reset and then Wipe Dalvik Cache.
• Now select - Install Zip from SDCard > Choose ZIP from SDCard.
• Now just choose the .zip file of the MIUI 4 ROM from your SD card, and then confirm your selection by selecting this option – Yes, Install__.ZIP.
• After that, select - ++++ Go Back ++++ and then Reboot System Now.