RSS isn't the way to subscribe to weblog comments. Email is (really, do you want to poll every hour for a feed that might only ever be updated twice?).
I've spent 10 minutes and set up scriptygoddess' subscribe to comments for moveable type, so now anyone can subscribe to receive comments added to any individual post. There are subscribe and unsubscribe buttons at the end of each comments form, and a one-click unsubscribe in each email. I've also edited the email template to include '[comment]' at the beginning of each subject line - this means you can set up a rule in your email client to filter all emails with subjects starting with '[comment]' into a special folder.
Also, Hublog's RSS feed now includes <comments> and <slash:comments> fields - supported by SharpReader at least. The first provides a link to the comments page for each entry, and the second provides the number of comments so far.