Here's a couple pictures of how my Dashcommand looks in the car (apologies for the glare, they were quick and dirty photos):
This is the default skin for Dashcommand. It has features such as data logging, and the ability to read additional data such as boost pressure, air/fuel, EGT, etc. by purchasing additional hardware that links a sensor to the computer.
Concerning running it on the factory nav, theDreamer is correct. You will need a converter type module. There are very few, such as the ones from this website:
Car Video Interfaces. MOST Adapters. GVIF
And, they are limited in vehicle compatibility, but you may have to pour through wiring diagrams and see if it is possible to trick the monitor into accepting that signal. I think Magden figured out a way to do that, but like I said, they are no more.
Also! I just remembered that Blitz made a similar product to the HKS Camp 2, called the R-Vit DS:
GTM Motorsports*::*ELECTRONICS*::*BLITZ R-Vit DS VEHICLE MONITORING SYSTEM
(found it for sale on GTM, so you could probably give them a call or something)
That seems to work similar to what you want.