Adding custom code to the front page

I’m finally migrating my site, using an old version of Comicpress, over to the latest Comicpress theme and Comic Easel plugin. One of the last items I still need to bring over is a custom piece of code I put into the old version of my site. Basically, my site needs to include the comment <!– Last Update: dd/MM/yyyy –> inside of the html, so that bots from TheWebcomicList can pick up on the fact that my comic has been updated. The current version of my site uses the following PHP code embedded into the index page:

<?php the_date(‘d/m/y’, ‘<!– Last Update: ‘, ‘ –>’); ?>

Now, after working with new version of Comicpress, I’m trying integrate this code more properly in my child theme. I don’t want to just hack it into the index.php file. I’m curious if you have any suggestions on how I should go about doing this. I was looking into using the add_action() WordPress function, but I’m not sure which Comicpress/Comic Easel function I’m supposed to integrate with. Any help would be appreciated.