>   I've tried all of the ecoff kernels (1.2Release, 1.2F, 1.2G, nfskernel,
> GENERIC, etc.) and ALL hang right after the "dc0 at mainbus" line.

> KN01 v6.71

Plug in your mouse...

At least, that sounds like exactly the problem I had when I installed
on my DS3100 with v6.71.
I tried net booting all the kernels, just as you did, and they all hung
on that same line.  After pulling my hair out for several hours, I
plugged in a mouse on a whim, and everything worked fine!
(Didn't think I would need it, since I wasn't going to be running X
initially...)

(I believe I tried this on a v7.01 prom as well, with the same results)

   -Jeff