This largely depends on if the Blogspot user allows people to subscribe to the comments. If they do, you will see the option when you click through to view the comments for the post.
At the bottom of the page (or on the side depending on their layout) there usually is a link in the form of:
Subscribe to: Post Comments (Atom)
That will lead to a link of the RSS for the comments on that post. It's in the following format:
http://example.blogspot.com/feeds/{generated-post-ID}/comments/default
Use the above as the RSS feed URL for your reader. Or if you want to have it sent to you through email, find a feed-to-email service that suits your needs.