I’m not sure if this is the only way to do it, but I’ve modified computed properties in customizations like this (the example is using the availableSorts computed property):
api.modifyClass('component:edit-category-settings', {
availableSorts: Ember.computed(function() {
let sorts = this._super();
let voteSort = {};
voteSort["name"] = "Votes";
voteSort["value"] = "votes";
sorts.push(voteSort);
return sorts;
})
});