Per documentation the datasource object can be defined in two different ways.
<li ui-scroll="item in datasource">{{item}}</li>
And the directive will first look for a property with the given name (datasource) on its $scope.
So to use scope-approach you need to declare
datasource object on scope of your controller and define method
get on it.
angular.module('application', ['ui.scroll']).controller('mainController', ...
$scope.datasource = {}
$scope.datasource.get = function...