simplest way is to buy din size/double din size pocket from honda that replaces your current pocket under the radio. Price wise, i think they are bout 80-100.

Or if you want something more, then as Dray_Templar suggested, carputer, like I had in my car. I would put the carputer in the glovebox, and touch screen on under the radio. This way everything will integrate nicely.

hope this helps
cheers