for Motorola Greco(XT3) user :
-Before you proceed, kindly copy the Rom to your root of SD card and rename it to update.zip.
-Please take note that your contacts and message will be erase. backup your contacts to your email account and use sms n2 manager to backup your sms.
1)You must make sure your Greco is root ( find Universal Androot )
2)Install ROM Manager and Flash the Clockwork recovery but after tat do not install direct from the menu.
3) go to recovery mode ( Press Power Button while holding Vol up Button + Camera Button)
4) use vol up or down, scroll to the " install zip from sdcard " and press Cam Button to enter
5)press Cam button again on "apply sdcard:update.zip"
6) Press ok to let it start flashing the ROM
7) if you see the progress bar is moving, that means it is started already.
8) once done, reboot
9) if you success, you will be able to see the CyanogenMod Loading screen.
If you stuck at the Motorola blinking load screen, dont worry. Below is the solution to it :
1) boot into recovery mode again
2) this time select wipe all data and cache
3) after that, reboot your device
4) this time for sure you can load successfully

enjoy ^^