i'm pretty sure that you are right - the HD can replace the CF altogether.
you can access it in the same way as you would the CF in your load/save
menus, and i think it even becomes default if no CF is inserted.
i'm not too sure about akai OS (probably won't be any upgrades for like 50
years anyway) but the JJ OS has the added feature of being a file you can
just load in the correct menu, rather than having to switch off the machine
and go through other process (the exact machinations off which currently
escape me).
so even JJ 3.06 (the free one) could help you out here... what OS are you
running now?
anyway, you should be sweet... and it's a hell of a lot easier than getting
the damn CF slot fixed!!

(mine took 8 mths here in oz

akai
ships parts here once every millenia.)