I just completed my install in an R53, but I was able to take advantage of the same cup-holder "hack" FireAnt used.
A few thoughts for the R56:
Do you have the center nav screen? If so, there has been work done on using that as a display, I believe you can find a ton of info over at NAM.
Another creative option may be to use one of the gloveboxes (you guys get two!) for the Mac Mini, then mount your monitor at an upward angle below the toggle switches.
You might even be able to "hinge" it so it's adjustable (thus leaving the use of the coin-cup holder).
As for the front end, well I am quite partial to Neon BoomBox, which is still under active (heavy) development. You can "customize" the main screen with a MC logo quite easily, in fact, I am including my own version.
To use my graphic, do this:
Save the image
Rename it from Clock.psd to Clock.png
Control-Click "Neon Boombox.app"
Choose "Show Package Contents"
Open "Contents", "Resources"
Drag replacement Clock.png file in.
This image fully supports the shifting palette used in NBB, don't let the Red throw you.