If I read this right you are trying to get podcasts (not being pulled via Zune) to sync onto your Zune?
Firstly make sure you podcast is in a format that is compatible with Zune (MP3 not AAC).
Next make sure the folder is listed to be monitored by Zune. That way it will import the files naturally.
Finally, if all else fails add you podcasts directly to Zune (for future downloads) by going to Collection > Podcasts > Add a Known Favorite and drop the URL into the box that pops up.
Hope this all helps.