Infiniti navigation question

Does anyone know what is required to add factory optional navigation after the fact? The M45 I am closing on was not equipped with this option but it is one I woulkd like to have. The non-navi vehicles still have the LCD in the dash. I have found the navi DVD drive. I am just curious what else I need

I looked into this and decided to go a different route. But when looking into it some people told me I could do it and others said I couldn't I bought the nav screen its larger than the non nav screen, nav is & and non nav is 5.5 i think, then I bought the dvd drive and gps receiver and bracket for it but after buying all of that decided to change plans and go with a car pc I am still working on the car pc right now but good luck with this and if you decide to tackle it and need some parts let me know I might decide to sell the parts as I do not need them.
 
Here's the link to my car pc build thread check it out if you want
[URL]http://www.vipstylecars.com/forums/showthread.php?p=232191#post232191[/URL]
I'll try to lend any help or info I can and once again goodluck with the project and I hope you get this done so someone can say they pulled it off and let everyone who says it cant be done that it can.