Be sure you have a spare PS2 keyboard.
With USB Legacy disabled you cannot get to BIOS with an USB keyboard
Darn, you're absolutely right
Further on in the thread I linked to before I found that someone was able to fix it by changing some kernel options. I'll have to dig some more to see what actually helped.
In another post in that same thread it was also mentioned that mounting a removable device with -o flosh
helped a lot.
Oh well, back to the drawing board