Refer to this
for details, reproduced a section here:
In order to aid people installing FreeBSD on their xbox, I have created
combined install/livecds to aid those willing to give FreeBSD/xbox a
try. The images can be used to boot a full multi-user FreeBSD
environment, but you can also boot directly into sysinstall to
install FreeBSD on your Xbox.
As I've recently merged Xbox support back to -STABLE, an ISO for
6-STABLE is also provided.
A list of the files and checksums is:
xbox-6stable-20060821.iso.bz2 - install/livecd for FreeBSD 6-STABLE
MD5 = 9afbab92bbb43a797753a941737ef0bb
SHA1 = 26908c6301484c133f23875a8136c2dbeb336e88
SHA256 = d67e51c2a37e14193a5cbfb49903899f60784e39f91888f8e0a48c85ee3eee46
xbox-7current-20060517.iso.bz2 - install/livecd for FreeBSD 7-CURRENT
MD5 = 82108c6112f8b39fb82e71fdc727704a
SHA1 = 83e40e292ac8ace395fcf199f1bb16b0a34531c5
SHA256 = 2176904283707273e7d62e31c516bc81c9a2021556bb84adbe23071ba9b8dd83
Some important points of attention:
(1) The loader used is Cromwell; the Cromwell version on the images has special
patches which do not appear in any official releases build . Therefore,
if you already use Cromwell on your Xbox, please chain-load the Cromwell on
the images beforing attempting to boot FreeBSD.
(2) 'patched' dashboard (the Xbox 'operating system') versions can directly
boot the /DEFAULT.XBE file on the CDROM. The official Dashboard will
fail to boot this, however, as the DEFAULT.XBE file is not signed
with any Microsoft-approved key. Booting this file will directly
start the FreeBSD-enabled Cromwell.
(3) There is no loader support. Any tunables must be set using kernel
options (such as the root device to use)
(4) The xbox is very picky on the media used. If you get random panics
or hangs during installation, try another brand of media.
(5) If you keep experiencing DMA errors or timeouts, please use a 80 pin
UDMA IDE cable. As there is no loader support, there is no way to
force ata(4) to use only UDMA2 modes.
(6) You currently need an USB keyboard; I'm planning to add
dhclient(8) and sshd(8) automatic startup to the liveCD later.
Anyway, feel free to give this a try and report any problems back to me.
I intend to clean up the script used to build the ISO images in a short
 Cromwell from xbox-linux.org CVS contains all patches required to be
able to boot the recent FreeBSD kernels. However, it does not
support direct booting from UFS partitions.
Item (2) is what you need, an Ndure based softmod will launch the dvd's default.xbe