Retrofitting headrest DVD system to an XC90

[Catchme]

I am interested in acquiring an XC90 with the rear headrest DVD entertainment system. I have been to two Volvo dealers and received differing advice on whether the Volvo system can or cannot be retroffited to an 05/55 on vehicle. One dealer says 'no problem sir', the other says that there was a change in the wiring loom on the 05/55 model and it cannot be done on the later models.

Anyone got a definitive answer for me?

Thanks in advance.