How pass args to wp_list_comments callback?

After looking at the wp_list_comments() and Walker_Comment sources I would assume the callback is what the Walker uses to render single comments. And the callback recieves three parameters $comment, $args, $depth when the Walker calls it.

Based on this, I assume you should be able to just push custom key-value pairs to your $args array and then have them available when the callback function is called.

This is slighty unfamiliar territory for me, so I may be mistaken.