It's got screw terminals, not punch downs. It's easy to see which leads to which pin. I cut out the wires for pins 3, 6, 7, and 8, and moved the terminals for the others so it would be easier to wire for 1245. Installed it. Wired it up. Moved the T1 router. And it didn't work.
I tried swapping 4 and 5, on the idea that maybe the old port wasn't linear. Didn't work.
Took the router back upstairs, was about to plug it back into the old port, when I noticed that I had the cable in the wrong port. I wasn't connecting to the WAN port. Took it back downstairs, plugged it in, no joy. Swapped 4 and 5 back to the original, and it worked. Sync! Connection! Joy!
So, the physical infrastructure for the network is now as it should be, with the exception of re-organizing the ports on the main switch.
The comcast installer is currently up on a ladder fighting with a filter; I've drilled a hole thru the side of the house to run the cable in through, and need to figure out how I'm going to set up the NAT. For the time being, I think I'll just change hladolet to use the cable modem's external IP, and route everything thru there. Later, I need to set up a triple-homed box so that local traffic to the servers routes directly there instead of over the internet.