1. Download the Debian CD1, grub4dos, Debian hd-media installer-i386's vmlinuz , initrd.gz, the partition must be the fat32.
2. Boot the grub4dos , and boot the debian he-media installer-i386's vmlinuz , initrd.gz.
Note: the he-media installer-i386's vmlinuz, initrd.gz and the debian's iso all in the U Disk's root directory.
Note: the grub4dos's manual , you can see the grub4dos docs, this article only put out the method of Install Debian.