on watch list of the entire show u can click next to the last episode u seen to mark up to that episode
the only downside is it doesnt show up on most watched shows and most watched networks
You can do so through the watch list. :)
If you click "view all" for one of your shows, you'll land on a page where you can mark all episodes of a show as watched in one click. Like here: http://www.tvmaze.com/watch/show?show_id=1
Aaaah! Nice :) Thanks for the answers! I'll delete the post.