Well, everything is installed!

Again, thanks this time to "maxtog" and "ALPHA556" for the inadvertent wiring help in their previous posts. ("Search" is your friend!)
Let me see if I can't post a little knowledge, too, based on my install.
Parts used:
(1) Givi E55 NT - the "tech," or black-striped one
(1) SW-MOTECH Steel Toprack
(1) Givi Topbox mounting Kit
(1) AdMore Run/Brake/Turn LED Kit
(1) Diet Coke (since we're dropping names...)
On the MOTECH rack: I wasn't (and still am not) sure about this rack. It looks great, but it's not the beefiest, either. Mainly, it was purchased because it was just over half the price of other choices. More on the rack later...

Installed, using 4 new bolts and included spacers, to get the height back with such a thin rack (without a single sheet of instructions provided, by the way):

So far, so good--nuts and bolts are easy!
Wait, I have to drill holes in my brand new box to install the AdMore kit?!? OK,...:

...but it was easy enough, and the LED's installed drama-free. Pretty cool that they include a drill bit, but could they at least include one that was straight and sharp? LOL... mine wiggled around like the shank was bent, and it wasn't even sharp enough to get through the plastic! Ultimately, it was completed with a very sharp and very straight pilot hole from a smaller bit, then opened using the provided bit.
Now the box is ready to go outside... and that's when the seat came off. OK, deep breath--time to dig. After removing my tool kit and tray, I gave that huge chunk of electronics a wiggle, and it lifted off the tabs:

Laying that aside and reaching farther back, you find what you're looking for, again, as pointed out by "maxtog" and "ALPHA556:" the 3-line brake/run/ground, and the two turn signal leads:

Using the AdMore-provided Posi-Locks--which, by the way, are probably THE CLEANEST method I've ever used to vampire-tap into existing lines--hookup was a snap. Remember, tap the existing line and set the body of the Posi-Lock before pinching the AdMore harness in the other end! If you do the AdMore harness side first, things get awfully twisted up

Another hole to drill?!?!? Ok,... Align everything, plan twice, check, check again, and decide where that plug is going to leave the box. For me, it was actually between the reinforcement ribs inside the box on the right side. The AdMore plug was the perfect width to fit between the ribs, which I figured would be an easy way to keep it from being beat-up by cargo. I also ran the line through the document holder on the inside, shielding it almost entirely from cargo. From the inside, I carefully routed the harness out the right-rear side of the seat.
...aaand, the finished product:

Summary:
LIKES: I have a HUGE topcase, and it looks great. The lighting is commendable during the day, and superb from dusk to dawn. I very much like the "triple blink" when you first hit the brakes, and like even more that it requires a 15-second reset to flash again (so as to not annoy traffic in stop-and-go conditions). I like how quickly the top case removes, too, should I wish to go,... top (case) less. Oh, and those Posi-Locks! Those are slick.
DISLIKES: Most notably, the fit of the box to the rack; there was way too much space under the box. Further, I can't tell if it's the rack or just the fit, but the tail-end of that box danced around like it was on a diving board for the first ride or two today, audibly rattling, even with my helmet on at speed. Later, I did the "soft side of Velcro tape" on the rack to minimize the rattle, and it's significantly reduced. Still, there's a bit too much flex at the back of the box for my tastes, and the box still installs relatively easily. I'm going to figure out if it's the rack or not, but my suspicion is that one of the thicker aluminum racks may be the answer... or maybe some thin carpet/felt/more Velcro on the deck. Or both. Or, I could file down that rear triangle so it's lower, but how much to remove? Anyway,... it's not a terminal failure.
So... that's it! I'll be out riding
