I've just tried Scotts variant of the madhatter patch, which in
my (1.179) version of machdep.c boiled down to remove a couple of
#ifdef MADHATTER's -- the rest of the patch was already present.

The machine (Quadra 610) is now running with the patch installed,
and without showing any problems.

The difference in dmesg output without and with the patch is

1c1
< NetBSD 1.3B (Q610) #98: Mon Feb  2 20:49:53 MET 1998
---
> NetBSD 1.3B (Q610) #99: Mon Feb  2 22:49:44 MET 1998
20c20
< ite at grf0 not configured
---
> ite0 at grf0 (minimal console)
36c36
< PRAM: 0x34d642a5, macos_boottime: 0x34d6429c.
---
> PRAM: 0x34d64eb9, macos_boottime: 0x34d64eb1.

The kernel was first completely rebuilt from today's current sources and
rebooted, then machdep.c was updated and a new kernel was built and
booted. 

The main difference is that ite0 is now configured.

The machine is happily running X in 1024x768, both with and without the
MADHATTER patch (internal video, 17" Multi-sync monitor with an SVGA
monitor cable adaptor) 

- Erik Bertelsen