Custom key bindings?

[eggbean]

If you want to add custom key bindings to manipulate with active selection, define them in the shift-select keymap (bindkey -M shift-select …​).

Could you please explain this a bit more? Can I add vim-like bindings that only work when text is selected by this plugin?

I would like to add x to put text into the kill buffer, like ctrl-w does. This would be more convenient me after navigating back using vim-mode temporarily (ctrl-x,ctrl-v). I can't remember how I enabled this key binding for temporary vim-mode.