[Plugin: Post Expirator] Enabling expiration by code

Hi

I’m looking for a way to enable the expiration by code. I use wp_insert_post to create new posts. Is there any other ways to accomplish enabling the expiration? I’m looking into the post-expirator.php file, but I can’t figure out. I don’t mind suggestions to edit the plugin file.

http://wordpress.org/extend/plugins/post-expirator/