I am interested in purchasing a presentation clicker but using it for other purposes, does anyone know if those things allow you to remap the buttons? Is it possible to use Keyboard Maestro to assign different keyboard combinations or mouse clicks to each button on the device?
There is no way to know for sure except by trying.
It depends very much on the device and how it works.
My guess would be that it just acts like a USB keyboard and sends keystrokes, in which case they can probably be detected by Keyboard Maestro, but whether they can be configured to use something that does not interfere with existing keystrokes and yet still can be detected by Keyboard Maestro is impossible to say without looking at each specific device.