The Nav System and Touchscreen on the X-Type does not have the composite video input that would be required to connect a reverse camera.
However, you could get a composite to RGB converter and relays (triggered from the reverse light) and wire it inline with the rgb signal cables coming out of the DVD navigation unit in the boot. You're possibly looking upwards of £50-£100 for the converter. You may also need a voltage regulator to power the converter, if it requires a 5V supply.
Introduction The purpose of this modification is to enable front and rear camera display on the centre console screen as inexpensively as possible. I have acquired additional components excluding Number Plate cameras and Lindy convertor to make up additional kits if anyone is interested...
www.jaguarforum.com
Note: a universal RGB video interface is not necessary. You can use just a basic composite to rgb converter and a couple of relays to handle the rgb signal switching
I just wired rear (and front) camera into the composite inputs on my JagDroid-upgraded Touchscreen.

And fitted the rear camera on the underside of my boot plinth.