Yes, you need to enable it in the cofiguration files, if its not enabled then you wont see the "rear entertainment" button on the touch screen, if the button is there then there is another fault.
No doubt your mate has done this, have a look in "display and/or modify vehicle configuration" on IDS, if the rear entertainment is not there then it's a byte number that needs to be changed, to get to this you need a seed code, the only way to get this is to fax or email land rover the code on the IDS screen and they will reply with the code to match your code, this code will change if IDS is turned off or the session is ended so it's important to leave IDS on and connected untill you receve the reply from land rover.
You will also need to know what byte number needs to be changed and to what, only land rover technical will know this!!!!