Help with install from USB

[Kevin Shanahan <kmshanah@ucwb.org.au>]

Hi,

I'm trying to install Sarge on a few new servers but I've run into some
problems. The servers have no cdrom and no floppy, so I'm installing
from a USB key.

I tried the official Sarge installer, but I can only get to the stage
where I need to partition the hard drives because they are not detected.
These systems have a newer Promise SATA TX2 controller which I think is
only detected/supported since Linux 2.6.12.

So, now I'm trying a current snapshot of the installer. Here's the files
and method I used to create the bootable USB key:

  # wget http://people.debian.org/~joeyh/d-i/images/2005-10-14/hd-media/boot.img.gz
  # wget http://cdimage.debian.org/debian-cd/3.1_r0a/i386/iso-cd/debian-31r0a-i386-netinst.iso
  # zcat boot.img.gz > /dev/sda
  # mount -t vfat /dev/sda /usbkey
  # cp debian-31r0a-i386-netinst.iso /usbkey
  # umount /usbkey

I can't get quite as far with the newer installer, because after booting
it's unable to mount the fat filesystem on the usbkey. (note: I'm not
actually in front of that particular machine now, but I've reproduced
the problem on the PC next to me). If I "Execute a shell" and try to
mount manually, I get the following:

  # mkdir /mnt
  # mount -t vfat /dev/discs/disc3/disc /mnt
  mount: Mounting /dev/discs/disc3/disc on /mnt failed: Invalid argument

These two lines get added to the end of dmesg every time I try to mount:

  # dmesg | tail -n 2
  Unable to load NLS charset cp437
  FAT: codepage cp437 not found

Now, I don't know if I've done something unusual or not. I dug up the
following changeset which leads me to believe I might have:

  http://svn.debian.org/wsvn/d-i/trunk/packages/kernel/kernel-wedge/modules/?rev=29778&sc=1

Okay, I'm probably being annoyingly verbose already, so can anyone tell
me what I can do to get past this point?

Thanks,
Kevin.