This chat is kind of old stuff because there are no more xbox in stores, but you never know when will it come in handy...
A while ago I've asked about the posibility to run XboxHDM from USB CD-ROM, which indeed is possible, but will never find the CD to be mounted, as it loads a kernel into memory, so stops using the cdrom as soon as it finishes loading isolinux and it's task (load the kernel), and will never search USB CDs, I haven't found if the kernel doesn't know about USB or what, but the script doesn't.
I've tried syslinux to load the hdm kernel, and it works too, but will still ask for the CD as source for files.
Why would I want to run it from USB???
Because lately, almost all motherboards only have 1 ATA interface, and some hard disk are so hard to get along with...
So if anyone has something to help, it will be appreciated.