1. Record your podcast as an MP3, Quicktime movie, whatever you like.
2. Upload it to the normal place. Copy the URL to the clipboard.
3. Create a new post.
4. Put the cursor on the top headline, click the suitcase icon in the left margin.
5. Add a new attribute called enclosure, its value is the URL on the clipboard.
6. Click Save.
If the URL points to something that Fargo is able to access, it will add enclosureLength and enclosureType attributes to the headline, automatically, and will generate an enclosure element on the RSS feed item. All of this will happen without you having to do anything.