You could do this by applying a CSS class to all your checkboxes inside the collection like "myCheckboxes". Then, create two buttons via custom HTML like this:

<button id="CheckAllButton" type="button" style="float:left;">Check All</button> <button style="float:right;" type="button" id="ClearAllButton">Clear All</button>

JavaScript for the buttons:

$(document).ready(function(){ 
$('#CheckAllButton').on("click", function(){
$('.myCheckboxes input').prop('checked', true).change();
});
$('#ClearAllButton').on("click", function(){
$('.myCheckboxes input').prop('checked', false).change();
});
});

Hope that helps!