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For the purpose you can use a bookmarklet, i.e. of Feedmyinbox.com.
Feed My Inbox is a Brightwurks idea.
Using The Feed My Inbox bookmarklet pops up a window where you can subscribe to any feed(s) on the page you are browsing. Simply drag the link to your browser bookmarks toolbar to install it.
Here is a detailed video from feedmyinbox.com
explaining the working.