Upgrading to a touchscreen with accessories

[Neil4152]

I have an X type 2004 2.0 diesel SE, I am very soon about to attempt to upgrade to a dash touchscreen, CD changer, phone module and sat nav module. The wiring does not seem to be in place on my current x type but I do have the leads on another X type (2.1 V6 sport) so will be attempting to transplant the wires over.
Any tips, tricks and advice will be gratefully received.