I wanted to post these only after the install was entirely done, but I'd have to wait at least another month before I'll have time for that. So, here are the first pics of my 4+ month "install from scratch" in my 2002 Mercedes-Benz E320 wagon.

This was my first install. Thanks to so many of you, I learned how to use a voltmeter, how to solder, the different wires in the harness, and much more. The install uses the stock Bose amp and speakers to keep the install cheap (~$80 in parts total) and "quick". Information on how to do the install was scraped together by the few people who said it was possible among the many many who said it was not (including an empeg installer from this forum; my main inspiration to try it).

Still to come:
Super stealth face place (and better pics of the Alpine's stealth).
Custom Volvo/Benz animated logo (for interop between my two cars).
Increase amp gain.
Take pictures with Filener yellow lens gel and green buttons (to match both the Volvo and Benz).

The wiring harness, carefully researched, tested, soldered, and heat shrunk:

The wires, source switcher, empeg harness, Alpine harness, and tap-ins for switched power and dimmer sense; all crammed into the dash:

The completed install. Empeg in place of the stock Becker (not Bose) headunit. Old Alpine, exactly the same as the one I bought new for my Volvo 4 years ago so I can reuse the same face for both, in place of the dash storage compartment. Everything fit so well it was practicaly ment to be this way.

Beautiful work!!! Very clean, very stealth install! It just looks so natural! Although I would recommend swapping that blue empeg face with a closer matching color...

I like it. Love the way you can flip the flap over the Alpine once you've taken the face off. Very stealthy

Very nice! The empeg is a stunning addition to that dash.

Now, where can one find some custom colored buttons?
I'd go with black!

Hmm, yeah black always looks good. But in this case, I think Red would match the wood trim and look perfect! I'm sure you're going to try out all the combinations anyway

Thanks. That's just my spare unit, photographed when I finished the install one worknight at 2:30am. When I have time, I'll use green buttons (to match the Volvo) and a Filener yellow gel (to match the Benz). Might have to mask off the gel around the VFD so it doesn't look so yellow.

I can't wait to find time to make the fake radio faceplate. It should fit perfectly over the sled and look really stock. Maybe October...

Final install pics and write up are here and here. Fake stock face plate image attached. Ha, the face plate is even missing a button, looking ratty so thieves are further deterred.