@elusznik: No, the hotfix (and only the hotfix, which explains the need for MRPI for everything else) is designed to be installed via "Update Your Kindle" (UYK) in the Settings menu.
The Hotfix also allows you to run MRPI without KUAL, via the
;log mrpi search string, which allows you to actually install KUAL on these devices (as it's no longer a simple Kindlet).
TL;DR: Factory Image ->
Factory JB ->
Hotfix ->
MRPI ->
KUAL Booklet w/ Coplate's patch -> Everything else