Box Deselect (MMB) Preference Changes? (Not Emulator)

Hello there! Starting blender up again, trying to quickly relearn the navigation. However, I am stuck with all these MMB actions. My mouse is missing a MMB, but however has two Side Mouse Buttons (SMB’s?). They are very comfortable to use, as they are right next to my thumb, and I have already changed all the navigation options in the preferences to the side mouse button (which it calls Button4).

I can’t seem to find where to change it so that my ‘Button4’ will deselect with the box marque. Does anyone know how to do this?

I have done some searching, but it seems all the responses I got were just telling people how to deselect with the box marque, not change its default.

Thanks,

Paniom