How to sync podcasts from iPod Classic to iTunes on other PC?
Found a tedious solution on the Internet:
Add all downloaded episodes to the new iTunes by copying the iTunes library and then select from the File menu "Add files to library". Go into each podcast's folder and select all files to add them to iTunes. Then iTunes will create the podcast with all these episodes, but you then have to subscribe to it again using the context menu on each podcast, so that it will be updated by iTunes.