The recent 2.0.6 firmware update had a number of improvements for TV Series, so you may want to read up on that. YAMJ has great support for TV Series, but it is via (X)HTML and Mede8er does not support that. Mede8er uses a folder structure with an about.jpg and folder.jpg (plus improvements mentioned in 2.0.6 firmware). I haven't looked very deeply into the 2.0.6 enhancements for series yet, but I suspect I will just stick to what I'm doing now...put each episode in it's own folder with an NFO file.
Series Name (in this directory include a folder.jpg for the whole series)
--Season 1 (in this directory include a folder.jpg for the first season)
--Season 2 (in this directory include a folder.jpg for the second season)
To keep Y2M/YAMJ acting on the files as movies (rather than switching to the TV series mode which is not compatible with the Mede8er), include the <movie> tag in each NFO file. At minimum...
...where IMDB_ID is the id number (including the tt) in IMDB for that particular episode.
For a specific example, Battlestar Galactica, Season 3, Episode 1. The folder structure would be like this...
The "Occupation (2006).nfo" file would contain at least the following...
After running Y2M/YAMJ, if you find some episodes are missing information, then just fill in the missing fields in the NFO for that particular episode and re-run Y2M/YAMJ. You can use something like YANFOE to update the NFOs if you like, but I prefer to just manually edit the NFO files (I find that easier and faster, but your experience may vary). It is a bit of work to setup, but once its done the results are great and you only need to do it once (for each series). To make it look even nicer (imho), I use the skin described here...http://www.mede8erforum.com/index.php/topic,8279.0.html
If you need help with NFO tags, use this...http://code.google.com/p/moviejukebox/wiki/NFO_Files#XBMC_NFO_movie_XML
Hope that helps.