as far as I know, you'll need something that takes a composite or svideo signal, and turns in into a component (RGB) video signal... a Pioneer AVC-RGB1 can be used, but they are hard to get a hold of as they are no longer made. ...and a 4PDT relay or switch to switch between the navi signal and the other signal.

On www.acura-cl.com or www.acura-tl.com you'll find more detailed instructions and a better idea of what is needed. There is a guy on www.acura-cl.com that has a module for adding video to Acura navi systems... his name is StreetEffectz... talk to him, hes very good with this.

good luck!