Actually, that's why I logged in tonight!
I figured out the problem with the system SE uses in FFXIV to rebind keys. They don't allow keys to bind to a key already in use, instead of clearing out the slot to which the key used to be bound. The trick is to use a temp key to swap keys around (like most programming languages would do to swap int values).
Example: I want to bind 'Num8' to Camera Down, but it is assigned to Movement Forward's secondary slot.
1) Select Movement Forward's secondary slot, then hit 'Num.' (the period on the number pad).
2) Select Camera Down's primary slot (which is currently 'K'), then hit 'Num8'.
3) Select Movement Forward's secondary slot, then hit 'K'.
It's slow, it's tedious as heck, but it works. I had my camera controls bound to Num8, Num4, Num2, and Num6 after a minute or so.
FFXI: Astyanax (Bismarck)