How to pass custom options from widget form to widget update callback?

I’ve added a few checkbox options to the default widget form. But I’m stuck on how to access these option states and pass them along during the widget save event (widget_update_callback) so that they can be saved by WP to the DB.

How do I pass my custom form values to WP to save as widget options for each widget?

In the first function, I’m Appending my checkbox options to all widgets control panels…

add_filter('in_widget_form', 'wse_widget_context_form');

function wse_widget_context_form(){

$checked = ' checked="checked"';
?>
<div class="wse_context">
    <ul>
        <li>Don't show this widget on: </li>
        <li><label><input value="on" type="checkbox" name="noHome" id="noHome"<?php if(isset($instance['noHome'])) echo $checked ?> />Home Page</label></li> 
        <li><label><input value="on" type="checkbox" name="noPosts" id="noPosts"<?php if(isset($instance['noPosts'])) echo $checked ?> /> Posts</label></li>
        <li><label><input value="on" type="checkbox" name="noPages" id="noPages"<?php if(isset($instance['noPages'])) echo $checked ?> /> Pages</label></li>
        <li><label><input value="on" type="checkbox" name="noCats" id="noCats"<?php if(isset($instance['noCats'])) echo $checked ?> /> Categories</label></li>
    </ul>
</div>

Callback function is below. $instance doesn’t contain the custom form values, only the default widget values (text and content). How do I append my custom options to $instance?

<?php
add_filter('widget_update_callback', 'wse_widget_context_callback');

function wse_widget_context_callback($instance){
    echo 'instance: '.$instance.'<br/>'; // returns array but no custom form values

}