The good news is that, today we can install and use Sony Xperia Z Keyboard app directly onto other devices running Android ICS or JB. This apk file is extracted from Sony Xperia Z devices.
How to Install Sony Xperia Z Keyboard:
The Xperia Z keyboard is available as a custom recovery flashable zip. Download it from above and copy to your Android device.
Download Xperia Z JB Keyboard_V.4_By Rizal Lovins Sundanesse.zip
Reboot your device into recovery mode.
After entering the CWM or TWRP recovery, backup your current ROM.
Return back to main menu in recovery and go to “Install” and select the “Xperia Z JB Keyboard_V.4_By Rizal Lovins Sundanesse.zip” file.
When the keyboard is installed, reboot the device.
Congrats, you have successfully installed the Xperia Z keyboard on your Android device.