It's possible. Not straight forward but not difficult either.
1. There are addons for smf to enable rss feeds for each forum. You need to install one of those if you don't have one already. (if you do then you should see the orange icon in firefox's address bar when browsing forums).
2. Then there are sites that can aggregate rss feeds from more sources (
http://www.google.com/reader is one example). You need to add the feeds of your desired forums into the reader.
3. The reader can also output rss feeds of the combined feeds you added.
4. Make the feeds addon of Etano read from the reader's feed and the posts will start appearing on the home page.
Alternatively we can read posts straight from smf's database and display them on your home page. This will not involve any rss feed, just good old php programming.