Adding a flag for comments

I have used statuses module when a comment is added to statuses mail is triggered as per the Statuses comments rule.
Now I want to allow user to turn on/off notifications for the comments posted to his/her comments.
Since statuses is not a content type so cannot add flag for it and so cannot add condition to the status comments rule for a flag.
Can anyone please help me in this?
How can I allow user to turn on/off notifications for statuses comments?

Thanks in advance