Fortunately, I ended up talking with a useful and clueful tech guy, and he hacked and slashed at their back end, while we chatted about fibre-to-the-home, metro area megabit wireless, self provisioning, and MOXI boxes (the thing that my employer makes) (he wants one).
Finally got it all working, and I have working DOCSIS.
Next step, port my home telephone over to a VoIP service. Then I shut down my POTS, my DSL, and my ISP.