Import subscribed without commenting from Mark Jaquith's plugin

Hi camu,

In the Mark Jaquith’s Subscribe to Comments users can subscribe to a post without commenting it (like in your plugin) and when so happens this record is added to wp_postmeta

post_id: the post id
meta_key: _sg_subscribe-to-comments
meta_value: the subscriber’s email

I have hundreds of these subscribtions, and they are not imported when I activate your great plugin.

How can import them with a mysql command and avoid duplications (if a post was already subscribed in wp_comments and so already imported)?

Thank you.
Julius

http://ww.wp.xz.cn/extend/plugins/subscribe-to-comments-reloaded/