how to use a single checkbox with wpalchemy?

WP Alchemy comes with example files that show the usage of virtually all field types;

Example;

<?php $mb->the_field('cb_single'); ?>
<input type="checkbox" name="<?php $mb->the_name(); ?>" value="abc"<?php $mb->the_checkbox_state('abc'); ?>/>

https://github.com/farinspace/wpalchemy/blob/master/wp-content/themes/mytheme/metaboxes/checkbox-meta.php#L9