As you can see in the function, you can pass a modifier name to windmove-default-keybindings
. In this case:
(windmove-default-keybindings 'hyper)
You can confirm that this works by using:
C-x@h<up>/<down>/<left>/<right>
And if your hyper modifier is working, then of course you can use:
<H-up> / <H-down> / <H-left> / <H-right>
(or you can just bind those directly, similarly to lawlist's answer; windmove just provides the function argument as a convenience)