Installing lenny on an USB flash drive

For testing and also just for the fun of it I'm trying to install lenny
on an USB flashdrive. No live system, just a "normal" install. The
installation scripts are not prepared for this, so among other error
messages grub installation on the flash drive fails.
Not a big deal as one should be able to use grub as already installed on
the hard disk. Current versions (0.97) will find the flash drive as e.g.
(hd1,0). But then the initrd was not properly built and did not set up
the device node. So the next step was to put a script into
/etc/initramfs-tools/scripts/local-premount/script.sh:
#!/bin/sh
mknod /dev/sdb1 b 8 17
#
and building a new initrd. But still the systems hangs on boot because
the device is created after the attempt to mount the root file system. So
"local-premount" is executed after mounting? Should be called "local-
postmount" then.
I'm able to boot the system by mounting /dev/sbd1 into the ramfs and than
doing a chroot and calling init.
But then there might be a more elegant solution for this which will allow
for booting without manual intervention.

Günther