Set Specific Podcasts to Show as TV Shows in iTunes, using AppleScript
The problem is that you can't change the "Media Kind" of a podcast track via AppleScript. For whatever reason, it seems to be some sort of special type that isn't exposed in the AppleScript dictionary.

The closest I've found to a method for doing this is this script in the Apple Support Forums that changes the Media Kind via GUI scripting. It seems to be set up for changing it to an Audiobook, so you'll have to modify it a bit, but it may be a decent starting point.