How do I map the keyboard soft keys when they give no event notification?

I have a Silitek SK-2501B keyboard which has soft keys for volume and play pause and all that stuff.

Only the mute and suspend button work. When I run the xev utility to determine the keycodes that the dead ones give off I does not return anything.

I assume next I should be looking for a driver but am unsure if it would be in X or in the kernel.

What debugging steps do I take when xev gives nothing?