Err, knc1 -- the JB is released as a zipped folder containing the jb.sh and bridge.sh and json_simple-1.1.jar and stuff (gandalf, bridge.conf, developer.keystore).
Just copy it over and run jb.sh manually instead of via the poison filename.bin
(Or kindletool-unpack the update bridge if you want to have fun, sure.
)
KUAL can be sideloaded to the userstore, once the JB is done that is the hard part.