It is an all or nothing propostion when it comes to moving iTunes content from one locale to another.
It can be done in the iTunes Preferences on the Advanced tab. You'd want to switch (change) the location of your iTunes Media folder.
Alternately, althogh less desirable in my opinion, you could uncheck the "Keep iTunes Media Folder Organized" option at which point you could manually move things around and have content in different places. But it would require an export and reimport to make that happen. And stuff that you download from the iTunes store, like Podcasts, will want to go into the Media folder to start with.
And while I am not familar with them, I believe there are some third party utilities out there that allow you to have more control over where iTunes content is stored. So you might want to look into those too.