It's actually a code = key keymap, this doesn't actually directly map to KOReader Events.
So, that's a no, not this way at least.
There's no built-in way to do that for keys like you can for gestures via the Gesture Manager.
But, if such an action already exists in Gesture Manager, you might be able to do so relatively trivially with a user patch.
If it doesn't exist in gesture Manager, you might be able to do so slightly less trivially via an user patch

.
I'm not in a position to check the code for any of these assumptions right now.