Note: I am in no way responsible for this ROM and do not take any credit for it. I am merely sharing for anyone who might be interested.

This is a link to the MIUI for the Defy. These links are from the official MIUI website.

Downloads:

ROM
Language Pack

Installation instructions:

1. Download Defy 2nd init installer 1.4 ONLY from here (1.8 might work as well, but 1.4 is recommended)
2. Run the 2nd init installer following the instructions closely.
3. Boot into Custom BootMenu by pressing volume down when device flashes
a blue led at boot
4. Backup your current ROM in the event you want to reflash
5. Select Recovery, Custom Recovery. Choose "Wipe Data/Cache" option. Let finish.
6. Choose Install .zip from SD Card, select MIUI rom .zip and let it finish.
7. Select the language pack and install this as well
8. If some text is still Chinese, go to Settings, Language and make
sure it is English UK or US. Boot into BootMenu and Custom Recovery one
last time and select "Wipe Cache" then go to Advanced and select "Wipe
Dalvik Cache". Reboot.
9. Done! Enjoy!

Notes: The GPS does not function well, but a fix is available. It can be found on the XDA forums. FM Radio does not work and is not supported at this time.