Easiest mehtod I know of is to get out the J C Whitney catalog and order their "extra loud flasher." As I recall, it costs less than ten dollars and for around thirty, they have one that plays a tune. You may want to check first to confirm that it will work in the new Honda.
The current issue of Motorhome Magazine has a story about how to add a buzzer to the turn signal circuit of a motorhome, and the same would apply to your car. It is really quite easy to do. You can get a copy at the news stand if you don't get one.