Disable mouse Input for StandaloneInputModule

Hi,
I have a system of buttons which can be navigated and selected/deselected by using the up/down arrow keys. This is linked to the EventSystem which is using StandaloneInputModule. This does the job that I want it to do, however, it also by default implements mouse controls (I.E. mouse hover highlights an object, clicking selects, etc.)

This function is not necessary for my game, and can cause problems with the number of items being selected at once, as well as the sounds being played on selection.
When I try to access the StandaloneInputModule, the Script is greyed out.

How can I edit this so that it only responds to keyboard input as opposed to keyboard and mouse input?

The input settings window provides support for Keyboard + Mouse, Mouse only, and Controller; but not Keyboard only.

User Recon472 provided a potential solution here, but I am unsure on how that code is to be implemented.

Hi man, I gave you tip on Unity answers, have a look.