WORKING WITH LOCKED BOOTLOADER!
0.) If you have stock kernel: Get ROOT and CWM for your ROM.
1.) Download the ROM, and copy it to your Memory Card.
2.) Restart your phone and get into CWM.
3.) Make a backup of your current ROM!
4.) Go into mounts and storage, and make format /cache, format /data and format /system. Go back, and go into Advanced, and make an Wipe Dalvik Cache.
5.) Go back to CWM Main Menu, and select install zip from sdcard. Choose the zip.
6.) If you finished with this, restart your phone.
Recommended to use it with .62 Baseband and Kernel!
Download links for it:
SK17i Mini Pro .62 Baseband and Kernel
ST15i Mini .62 Baseband and Kernel
WT19i Live with Walkman .62 Baseband and Kernel
Install it with Flashtool.