How do I subscribe to podcast in iTunes remotely?
I don’t know of a software that can do that automatically, however you have two choices:

1) If you want the podcast to be downloaded and ready, you will have to remote control your home PC and do it normally as if you were sitting in front of your computer. (Either through VNC or Windows Remote Connection)

2) If you don’t mind doing it when you get to your home, you can use a service like Dropbox and have a text file with the URLs. Since Dropbox will sync automatically, you can open the file when you get home and the urls will be there. Or use a service like Instapaper to save the URLs that will be ready when you get home to be added to your home iTunes.