A ver copio aquí los pasos que yo sigo que son exactamente los del post de XDA:
Código:
FLASH INSTRUCTION FOR THE FIRST FLASH
Download the CM10 Android 4.2 Mod
Download the 4.1.2 stripped GApps
Download INT2EXT4+
Put all the three zips into the root directory of your sdcard: /storage/sdcard0
Perform a full wipe
"advanced" > "wipe battery stats"&"wipe dalvik cache"
"mounts and storage" > format everything except sdcard
"wipe cache partition"
Flash all the three zips with the Recovery with "install zip from sdcard" > "choose zip from sdcard"
Go to "mounts and storage" > "format /sd-ext" to get the INT2EXT4+ Script working
Reboot
Download the new Google Now
Open a Data Manager, navigate to the downloaded GNow.apk, tap on it and install it
Set up your Google Account via Settings
Enjoy the new flavour of Android 4.2
Están en Ingles pero vamos que no será muy dificil de hacer.