Once you've figured that out, if you had USBNetwork installed, it will be able to load an 'emergency' shell script at boot [provided the system doesn't crash earlier that the USBNet startup script runs, which happens to be somewhat late in the boot process, although still as soon as the userstore is available], in which you'll have to write a simple shell script to restore what you broke. Having a backup of a full 2.5.8 rootfs image would of course be of tremendous help. (Barring that, provided you only need OSS stuff, I do have a live 2.5.8 system that I can pilfer).
(Path to said script, which *must* be exact:
/mnt/us/usbnet/bin/emergency.sh)
Start by writing a simple "Hello world" script w/ an eips call to check if your device dies earlier than that.
It risks getting annoying fast, because of the need to do a factory reset to actually access the USB drive, but at least that's something
.