For anyone else looking into this, I found a way to get a paid podcast syscing in the app. works really well with my coast to coast am subscription. In itunes, go file -> add new podcast. This pops up a window where you can type in the url. Paste the url into the window, replaceing the itpc:// with http://. In the url, add your login info like this:
http://username:password@rss.example.com/
if your user name is an email address, replace the @ with the url code like this:
http://myname%40gmail.com:password@rss.example.com/
This will add the podcast to itunes, with no need to ever sign into it again. plug in your iphone/ipod and sync 1 episode to your device so that it shows up in your podcast list on the device. It will now behave exactly the same as any other free podcast within the app.
happy podcasting!