I used Safari to bookmark the RSS feed I was interested in following, though I use Google Reader for my other RSS feeds. If you use Safari to read all your RSS feeds, you need to specify which RSS feed to process in the workflow. I then created a workflow that opens Safari and Transmission, processes unread RSS feeds from Safari, downloads the torrents, and marks RSS articles as read.
The workflow is saved as an application which is then launched automatically at set times by iCal alarms. Transmission's watch folder is set to the same folder as Safari's downloads, so Transmission automatically detects the torrents and starts downloading away.
Details on the workflow:
1. Get Specified Finder Items: Safari and Transmission
2. Open Finder Items -- to launch both apps
3. Get Feeds From Safari: check the Only return feeds with unread entries box.
4. Filter Articles: Any conditions are true, with one condition of Status -- is -- unread.
5. Mark Articles: Status = Read
6. Get Link URLs From Articles: uncheck the Only return URLs in the same domain box.
7. Display Webpages
I saved this as an application, and have iCal open it several times during the day.