it's no big deal
just hide an inverter below the cube somehow and then get a vga to rca converter, or a card for the cube

then just wire it up in the back of the nav system tied into the dvd input (i believe there is one there, if not o well, tie it into the monitor)

there are sellers online of systems that make flat paneles and such touch screens that pllug into usb ports with software, try and find a universal one that is smalll enough for your screen.

this task would be much easier wiht a PC than a mac, just to tell you.

even if you were to run linux instead of windows, a PC would be 30 times easeir casue of perhiperal support, as a computer guy you should know that mac's arent worth the trouble anymore, they are just unix systems now that have no hardware support.
i suggest buying somthing like a bragbox or a mini box for use