Power connection: on the truck, I ran the power cables in the gap along the side of the engine to the rubber stopper where the FM antenna coax went through. When I removed the kit, it was painfully obvious that it had been too close to the engine ... the loom was pretty badly melted and deformed, but it did its job and the wiring was all right. This time, I followed the FM antenna coax instead ...much farther from the engine. You can see the disconnect for the FM coax in the lower left of this picture.
Ground to the front body lug. Both the 12v and ground wires pass through the firewall at the rubber stopper where the FM coax comes through. Used the knitting-needle trick to punch holes in the stopper and make a nice snug fit.
This is the custom-made bracket that holds the control heads in the place where the ashtray used to be. I removed the ashtray, and drilled two holes in the metal panel to accept bolts to hold the bracket. The bracket is designed to accept bolts that I added to the backs of the CDM control heads, which insert through the bracket and are fastened with lock washers and wing nuts.
Once you remove the dash trim, you can remove two screws which allow you to drop the metal ashtray panel down to access it from the top, which is necessary to get decent-sized bolts and washer in there. For whatever reason, the ashtray panel is spot-welded in the back (toward the front of the vehicle) but once the two screws are removed, you can gently bend it down far enough to get good access:
Dropping in the bolts and washers:
The bracket installed on the ashtray panel, ready to be gently lifted back into place and refastened:
The installed bracket with the dash trim back in place:
The next step involves removing the center console. This is easy: just remove the three screws that hold the arm rest in place, and remove the single bolt hidden under the tray mat. With that done, it lifts right out. Here's the bracket in place, and the control head cables and power lead (with Powerpoles installed) laying in place:
At the other end of the center console, I used a second custom-made bracket to attach the two CDM bodies to the metal bracket that supports the arm rest. The "red" radio is programmed for receive-only on the AAR railroad band, and the "blue" radio is programmed for the 2-meter ham band. The radio bracket is made so that the bolts screwed into the radios line up with the recessed grooves on the armrest bracket:
While out, the center console gets a notch cut into the front corner to provide room for the power, control head, and speaker leads. Also note the aftermarket battery posts that haven't been installed yet. (Even if I didn't have radios to connect, I'd still replace those tiny, cheap OEM posts on any vehicle I own.)
And a hole drilled in the back corner to allow entrance of the antenna coax:
The next portion was getting the holes drilled for the Larsen NMOKFUD antenna mounts and the routing of the coax. I was fortunate that both runs of coax from the old truck were still usable in the Blazer. I didn't even have to remove the Mini-UHF connectors. Two holes were drilled, with a Larsen quarter-wave 2-meter antenna going in the front, and a Larsen 5/8 wave tuned for the railroad band going toward the back.
It was also fortunate that I didn't need to completely remove the headliner. Simply unscrewing the visor, roof handle, and courtesy hangers on the passenger side allowed me enough slack to get the holes drilled, filed, and route the coax. I had to pull out the front window column trim, and the center window column trim, which necessitated removing the bolt holding the seat belt in place (it's a Torx 50, BTW). With the column loose, I routed the coax and taped it in place with aluminum tape (the stuff lasts forever). A hole similar to the one drilled in the back corner of the center console allows the coax to exit the column trim.
A short run of heavy rubber tubing protects the coax for the couple of feet it needs to run across the floor behind the passenger seat:
With the center console back in place, this is what you see when you lift the armrest. Note the 4-way Powerpole splitter for power distribution, and the black and white Powerpole connector for the speaker.
And this is the finished install on the dash. The 13w external speaker is connected to the "red" railroad radio, allowing me to turn it up nice and loud and still be able to hear it while out of the vehicle. The speaker lead follows the control head and power lead underneath the center console to the radio body.
Obligatory antenna shot:

Hope this install write-up will be of value to someone in the future. Comments appreciated.
Scott KC9LQV
aka sataraid1