You talking about transplanting a nav-display setup from an E38 into an one that didn't have it? If so, I don't know if that would have had touch-screen capability or not. I think the issue there is the modules may be coded specific to each vehicle, and not just a plug-n-play swap, although something like that might also get into total dash or center console swap or something like that. As for aftermarket install, don't know if there's much of anything specific, I'm not sure any of the components to an E38's audio/electronic setup are easily replaceable, I think they're non-standard modules, tied into the car's other control and electronic systems, and are not any sort of standard size, like DIN-sized radio units. Given smart phone capabilities, depending on what you're hoping to accomplish, getting phone connectivity might be an option. http://www.audiovoxoei.com/ see crutchfield.com also
There are aftermarket options for this but will require modifications to make it work. There are also retrofit kits out there to install nav on a vehicle not equipped with it. Which route are you looking to take?
