With ISBoxer, you can create sets of Keymaps.
The default is General, Control and FTL DPS.
But you can make your own.

You can also have Keymaps enable or disable individual Keymaps or groups of Keymaps.

I'm not sure what the equivalent is in HKN, but have been told if you can think of what you want, there's a way for HKN or IS to do it.

Create four sets of Keymaps.
Call them TopLeft, TopRight, BottomLeft and BottomRight.
Have all of the binds you want within each set.

When a given toon switches to whatever region.
On the keybind which controls the PiP swap.
Have a Keymap, which controls the state of the four sets of Keymaps.
It will enable one and disable the other three.

Something to that effect, would be my guess.