Question about keymapping

[Ruillas]

Does anyone know if there's a plugin, or if it would be possible to make a plugin, that allows you to assign the mouse wheel function to a hotbar slot? For example, I'd like to assign alt + mousewheel up to a bar slot and alt + mousewheel down to a slot. I was able to do this with the WoW keymap options but for some reason Lotro will not let me. Thanks.