Is it possible to install from a USB disk with sysinstall or Grub?

[Ottavio Caruso <ottavio2006-usenet2012%yahoo.com@localhost>]

Hello,

I'm trying to install the amd-64 port onto my ageing Thinkpad X61,
which has no cdrom/dvd slot.

I was wondering if I could reuse of my usb flash drives with Sysrescd
on it, without sacrificing a new one.

I've downloaded both the .iso and the usb image and I can launch them
fine using syslinux and memdisk:

LABEL netbsd
MENU LABEL 8) Netbsd install
LINUX memdisk
INITRD /netbsd/NetBSD-6.1.2-amd64.iso
APPEND iso raw
TEXT HELP
Boot into Netbsd iso installer
ENDTEXT

or in the case of the usb image:

LABEL netbsd
MENU LABEL 8) Netbsd install
LINUX memdisk
INITRD /netbsd/NetBSD-6.1.2-amd64-install.img
APPEND harddisk raw
TEXT HELP
Boot into Netbsd usb installer
ENDTEXT

In both cases, if is use the ACPI option the installer hangs trying to
find a boot and root device.
If I select the second or third option (no ACPI) the installer hangs
even before reaching that stage.

Has anybody got a clue of how to give the right parameters?

A second option would be creating a second partition on the USB drive
and 'dd' the image over there, but in this case how would I boot the
second partition?

Thanks for your input.

-- 
Ottavio