Unzip this file to a place of your choice (I have a temp folder I use myself). In the C404IFR Panel folder you will find 2 folders. Place the panel.1 folder into your .../FS9/aircraft/c404 folder and place the CONTENTS of the Gauges folder into your FS9/gauges folder.
To use the panel in any original or repaint versions of Mikes aircraft just open up the aircraft.cfg in the main c404 folder and replace the line panel= with panel=1 for each of the [flighsim.xx] entries you want to use it with.
I highly recommend reading Don's original doc's on using his GNS430, especially if you're only used to using the stock GPS500. If anyone is looking for a 'Nav/GPS' switch, it's an integral part of the GNS430 functions.
That's it.